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20" iMac G5 overheating?

Message #1 - Posted 2007/04/19 - Paul Fuchs

I boosted my RAM two weeks ago from 768MB to 1.5 GB. The machine has now started to shut itself off occassionally. No other problem. Assume it's overheating. First gen iMac G5's, especially the 20 ", are known for this. I don't get any fan noise though.

I guess my question is that I have that CPU heat widget. What is considered a normal operating CPU temp and what is a shutdown temp?

TIA

Message #2 - Posted 2007/04/20 - Jolly Roger

On 2007-04-19 21:50:40 -0500, Paul Fuchs said:

I boosted my RAM two weeks ago from 768MB to 1.5 GB. The machine has now started to shut itself off occassionally. No other problem. Assume it's overheating.

Seems like you might instead assume one of the RAM chips you added is defective...

JR

Message #3 - Posted 2007/04/20 - Paul Fuchs

Jolly Roger wrote:

On 2007-04-19 21:50:40 -0500, Paul Fuchs said:

I boosted my RAM two weeks ago from 768MB to 1.5 GB. The machine has now started to shut itself off occassionally. No other problem. Assume it's overheating.

Seems like you might instead assume one of the RAM chips you added is defective...

Well, I thought of this, but then thought it very unlikely that this would result in the machine shutting down completely. I would expect some sort of freeze.

I am monitoring the CPU heat and seeing if I can correlate it with the shutdown. It's getting hot here (USVI), G5 heat control on 1st gen iMacs was marginal, and the added power consumption from replacing a 256 MB with a 1 GB chip might have pushed it over the edge.

Once again, anyone know at what temperature this machine should shut down?

Message #4 - Posted 2007/04/20 - Fred Moore

Previously, Paul Fuchs wrote:

Jolly Roger wrote:

On 2007-04-19 21:50:40 -0500, Paul Fuchs said:

I boosted my RAM two weeks ago from 768MB to 1.5 GB. The machine has now started to shut itself off occassionally. No other problem. Assume it's overheating.

Seems like you might instead assume one of the RAM chips you added is defective...

Well, I thought of this, but then thought it very unlikely that this would result in the machine shutting down completely. I would expect some sort of freeze.

Did you take the back off and look for bulging capacitors in the power supply area? (Google for pictures and other info). Intermittent shutdowns is a symptom of this problem. It could just be coincidental with the RAM install. The issue is covered by a warranty extension if you have a rev 1 G5 iMac with the right serial number.

--Fred

Message #5 - Posted 2007/04/20 - Jolly Roger

On 2007-04-20 06:54:30 -0500, Paul Fuchs said:

Jolly Roger wrote:

On 2007-04-19 21:50:40 -0500, Paul Fuchs said:

I boosted my RAM two weeks ago from 768MB to 1.5 GB. The machine has now started to shut itself off occassionally. No other problem. Assume it's overheating.

Seems like you might instead assume one of the RAM chips you added is defective...

Well, I thought of this, but then thought it very unlikely that this would result in the machine shutting down completely. I would expect some sort of freeze.

Yeah, if you mean it shuts itself down "normally" (as if you told it to shut down), you may be right.

I am monitoring the CPU heat and seeing if I can correlate it with the shutdown. It's getting hot here (USVI), G5 heat control on 1st gen iMacs was marginal, and the added power consumption from replacing a 256 MB with a 1 GB chip might have pushed it over the edge.

Once again, anyone know at what temperature this machine should shut down?

I don't think it's documented anywhere, but I could be wrong. Your best bet might bee to call Apple support and ask them though.

JR

Message #6 - Posted 2007/04/20 - Paul Fuchs

Fred Moore wrote:

Previously, Paul Fuchs wrote:

Jolly Roger wrote:

On 2007-04-19 21:50:40 -0500, Paul Fuchs said:

I boosted my RAM two weeks ago from 768MB to 1.5 GB. The machine has now started to shut itself off occassionally. No other problem. Assume it's overheating.

Seems like you might instead assume one of the RAM chips you added is defective...

Well, I thought of this, but then thought it very unlikely that this would result in the machine shutting down completely. I would expect some sort of freeze.

Did you take the back off and look for bulging capacitors in the power supply area? (Google for pictures and other info). Intermittent shutdowns is a symptom of this problem. It could just be coincidental with the RAM install. The issue is covered by a warranty extension if you have a rev 1 G5 iMac with the right serial number.

--Fred

No but I will. I do have the rev 1 :-( and our one authorized dealer/repair station in the USVI STT is not that great. I had a situation about a year ago when the machine would shut itself down, usually while still booting, but never in more than 3 minutes from start up. Brought it in under the one year extended warranty ( It was about 16 months old at the time and I didn't have Apple Care due to travelling screw-ups).

They kept it for a month and then returned it with purportedly a new logic board. Didn't affect the problem whatsever. Brought it back. They but in a new power supply. Only have had one problem since then until now. I returned from a six week trip during which the iMac was unplugged and stored, and I had absolutely no sound. The analog sound option would not appear in system preferences. Definately a hardware problem, probably in the logic board. I just bought an iMic II for $30, and haven't had a problem since then until now.

Regarding the current shut down problem, the cpu has read as high as 70 C. I have only had the problem once since I reported it to the group. This morning. It just wouldn't wake up from sleep. It was pushing 70 c when I put it to sleep. But previous shut downs have occurred while active. Haven't heard any extra fans kick in.

I found this on a group discussion going back 18 months:

________
No, heat issues are a serious problem (with rev 1 G5 iMacs). With 1GB modules cranking out
nearly 20W each, it does not take much memory to create a significant heat source within a system. The architecture of the module affects both heat output and airflow.
______________

I don't know whether this is accurate about a 1 GB RAM chip using 20 watts of energy (which would converted completely to heat), but it sounds plausable, and could be the cause of my new problem.

Has anyone had any experience of bad ram module, or two in compatable RAM modules in the slots actually shutting down a machine - turning it off, that is?

When I put in the new chip, replacing a 256 MB with a 1 GB, the innards were quite clean, but I will check around the power supply for bad capacitors.

Since I cannot hear any additional fan noise when the temp approaches 70 C, maybe the relay that boosts the speed is defective. I guess the sensor is ok as it is presumably the same one that feeds the widget.

TIA

Message #7 - Posted 2007/04/20 - Adrian

Paul Fuchs wrote:

Regarding the current shut down problem, the cpu has read as high as 70 C. I have only had the problem once since I reported it to the group. This morning. It just wouldn't wake up from sleep. It was pushing 70 c when I put it to sleep. But previous shut downs have occurred while active. Haven't heard any extra fans kick in.

70c CPU temp on a G5 is not too high. When really pushing both processors on my dual Powermac G5 I've seen up to a sustained 85-86c on processor A ... fans and pumps running of course ... me feeling uncomfortable but the G5s survived intact!

Adrian

Message #8 - Posted 2007/04/20 - matt neuburg

Paul Fuchs wrote:

I boosted my RAM two weeks ago from 768MB to 1.5 GB. The machine has now started to shut itself off occassionally. No other problem. Assume it's overheating.

I wouldn't assume that. I would assume that the power supply is about to go. These machines are famous for that. m.

matt neuburg, phd = matt@tidbits.com, http://www.tidbits.com/matt/ Tiger - http://www.takecontrolbooks.com/tiger-customizing.html AppleScript - http://www.amazon.com/gp/product/0596102119 Read TidBITS! It's free and smart. http://www.tidbits.com

Message #9 - Posted 2007/04/20 - John White

Previously, Adrian wrote:

Paul Fuchs wrote:

Regarding the current shut down problem, the cpu has read as high as 70 C. I have only had the problem once since I reported it to the group. This morning. It just wouldn't wake up from sleep. It was pushing 70 c when I put it to sleep. But previous shut downs have occurred while active. Haven't heard any extra fans kick in.

70c CPU temp on a G5 is not too high. When really pushing both processors on my dual Powermac G5 I've seen up to a sustained 85-86c on processor A ... fans and pumps running of course ... me feeling uncomfortable but the G5s survived intact!

Take a look at http://docs.info.apple.com/article.html?artnum=86815 It says that there's an LED in an iMac G5 that lights when an over-temperature condition is detected.

Incidentally, my 1st-generation iMac G5 runs up to 70 degrees C CPU temperature quite often.

-John-

Message #10 - Posted 2007/04/20 - The New Guy

Regarding the current shut down problem, the cpu has read as high as 70 C. I have only had the problem once since I reported it to the group. This morning. It just wouldn't wake up from sleep. It was pushing 70 c when I put it to sleep. But previous shut downs have occurred while active. Haven't heard any extra fans kick in.

70c CPU temp on a G5 is not too high. When really pushing both processors on my dual Powermac G5 I've seen up to a sustained 85-86c on processor A ... fans and pumps running of course ... me feeling uncomfortable but the G5s survived intact!

That just seems like really bad cooling! But cooling was never Apple's strong point. I wonder if its possible to replace the cpu heat sink with something better? The Mac Pro uses what looks like a similar design to the Scythe Ninja. Very good design. Or just take the back off and see if that makes a difference. It probably will. But it would be interesting to know by how much. Be sure to note the ambient room temperature.

Message #11 - Posted 2007/04/20 - Adrian

The New Guy wrote:

That just seems like really bad cooling! But cooling was never Apple's strong point. I wonder if its possible to replace the cpu heat sink with something better?

Have you seen inside a Powermac G5? All metal fully perforated design, liquid cooling radiators and fans on both processors ... 9 fans in the case ... it heats my room quite nicely! Improving the cooling in one of these things would be quite an achievement! Anyway, given that it has performed flawlessly over the past 2 and a half years it would seem that it is dealing with it's cooling in the way it was designed.

Adrian

Message #12 - Posted 2007/04/20 - Paul Fuchs

matt neuburg wrote:

Paul Fuchs wrote:

I boosted my RAM two weeks ago from 768MB to 1.5 GB. The machine has now started to shut itself off occassionally. No other problem. Assume it's overheating.

I wouldn't assume that. I would assume that the power supply is about to go. These machines are famous for that. m.

You are probably right. Had it replaced once already under the extended warranty :-(

Message #13 - Posted 2007/04/20 - Paul Fuchs

John White wrote:

Previously, Adrian wrote:

Paul Fuchs wrote:

Regarding the current shut down problem, the cpu has read as high as 70 C. I have only had the problem once since I reported it to the group. This morning. It just wouldn't wake up from sleep. It was pushing 70 c when I put it to sleep. But previous shut downs have occurred while active. Haven't heard any extra fans kick in.

70c CPU temp on a G5 is not too high. When really pushing both processors on my dual Powermac G5 I've seen up to a sustained 85-86c on processor A ... fans and pumps running of course ... me feeling uncomfortable but the G5s survived intact!

Take a look at http://docs.info.apple.com/article.html?artnum=86815 It says that there's an LED in an iMac G5 that lights when an over-temperature condition is detected.

Incidentally, my 1st-generation iMac G5 runs up to 70 degrees C CPU temperature quite often.

-John-

Thank you.

Message #14 - Posted 2007/04/21 - The New Guy

That just seems like really bad cooling! But cooling was never Apple's strong point. I wonder if its possible to replace the cpu heat sink with something better?

Have you seen inside a Powermac G5? All metal fully perforated design, liquid cooling radiators and fans on both processors ... 9 fans in the case ... it heats my room quite nicely!

That is exactly what I'm talking about. Very bad cooling design. If you have hot air exiting, its not being cooled properly. The problem with so many case designs is they try to cool components with warmed interior case air. Which, when you think about it, is rather difficult. 9 fans....whatever for? How many heat generators are there in that box? CPU (which is liquid cooled in the G5 tower isn't it?), video card, hard drive(s), and to a very minor extent the ram, chipset and optical drive (when its working).

A good design would take exterior air to cool the heat generator and then immediately vent it out. Unfortunately, few designs do this. People like the traditional tower computer shape, unfortunately. A good design would have the hard drives in a separate enclosure to absorb the high pitched whine they usually generate with a different type of cooling design than the cpu and video card. The cpu fan produces a lower frequency of noise than the hard drives so the sound absorption used needs to be different. And the power supply should be external as any power supply using positive cooling can adequately be cooled with a 120mm fan run on 5 volts, which is inaudible.

The Mac Pro, while still a lousy design for cooling, is much improved. At least they know better than to use sub 120mm fans. Check out the hard drive cooling. The first drive gets the fan, and the last drive cooks. I don't know why Apple is so short sighted in the cooling department. But they've been that way forever. How many hard drives were cooked in the G5 tower? Squashed up there in the corner.

Has everyone forgot that heat rises?

Improving the cooling in one of
these things would be quite an achievement! Anyway, given that it has performed flawlessly over the past 2 and a half years it would seem that it is dealing with it's cooling in the way it was designed.

If you have a CPU temp of about 35c and interior air about the same, you have good cooling. Otherwise it sucks and your components will die way before they should. To open your eyes, check out: http://silentpcreview.com About fans in general:
http://www.silentpcreview.com/article690-page1.html They combine silence with cooling. Now a lot of their opinions are still conformist, but you get the principles nevertheless. So few manufacturers are willing to step out into uncharted territory with new designs. Someone once said,
"Don't worry about someone stealing your design. If its any good, you'll have to shove it down their throats."
It says a lot about how open minded people are to new ideas. I guess, sometimes to accept a new design as superior, one has to admit their present design that they adore is inferior and that can bruise a timid ego.

Message #15 - Posted 2007/04/21 - Dave Balderstone

Previously, The New Guy wrote:

If
you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

I am extraordinarily patient, provided I get my own way in the end. - Margaret Thatcher

Message #16 - Posted 2007/04/21 - Mike Rosenberg

Dave Balderstone wrote:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

I propose that it be used for cooking. Apple should start selling the iGrill, a device resembling a George Foreman grill, that connects to a Mac and uses its heat for cooking burgers and stuff.

<http://designsbymike.biz/macconsultshop.shtml> Mac-themed T-shirts <http://designsbymike.biz/musings.shtml> Mostly muckraking T-shirts <http://designsbymike.biz/prius.shtml> Prius shirts & bumper stickers <http://cafepress.com/comedancing> Ballroom dance-themed shirts & gift

Message #17 - Posted 2007/04/21 - Adrian

The New Guy wrote:

That is exactly what I'm talking about. Very bad cooling design. If you have hot air exiting, its not being cooled properly. The problem with so many case designs is they try to cool components with warmed interior case air. Which, when you think about it, is rather difficult. 9 fans....whatever for? How many heat generators are there in that box? CPU (which is liquid cooled in the G5 tower isn't it?), video card, hard drive(s), and to a very minor extent the ram, chipset and optical drive (when its working).

A good design would take exterior air to cool the heat generator and then immediately vent it out. Unfortunately, few designs do this.

You have some strange notions! Of course cool exterior air is used ... why the heck do you think the entire front of the G5/MacPro tower is perforated? It's so fresh cool air can be drawn in, used for cooling, and expelled out the back. The effectiveness of this system can easily be felt by placing your hand at the front where air goes in, and then at the back where the air comes out ... believe me there's no doubt that there is heat being removed! Where do you get the idea that it's using warmed interior air for cooling?

Adrian

Message #18 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 09:37:49 -0500, The New Guy said:

That just seems like really bad cooling! But cooling was never Apple's strong point. I wonder if its possible to replace the cpu heat sink with something better?

Have you seen inside a Powermac G5? All metal fully perforated design, liquid cooling radiators and fans on both processors ... 9 fans in the case ... it heats my room quite nicely!

That is exactly what I'm talking about. Very bad cooling design. If you have hot air exiting, its not being cooled properly.

LOL... You're kidding, right?

The idea of any cooling system is to displace the heat - in other words, move the heat from one undesirable place to another more desirable place. I would say the fact that the G5/Pro displaces as much heat as it does shows that it is in fact doing a *great* job at cooling the components of the G5/Pro. Do you actually propose that heat should stay *inside* the machine? Or are you saying the fact that the components generate heat to begin with somehow equates to bad cooling?

)

The problem
with so many case designs is they try to cool components with warmed interior case air.

This is precisely what the G5/Pro cooling system does *not* do. It is designed to move cooler air from the outside of the machine (in front of it) through the front vent, across all heat-generating components, and right out the back, and in a very efficient manner. It's pretty much a straight line from front to back. That's why it displaces as much heat as it does.

Which, when you think about it, is rather difficult. 9 fans....whatever for?

To ensure there is enough constant air flow to displace heat in an efficient manner. Why else?

How many heat generators are
there in that box? CPU (which is liquid cooled in the G5 tower isn't it?), video card, hard drive(s), and to a very minor extent the ram, chipset and optical drive (when its working).

You forgot the power supply.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

Which is exactly what the G5/Pro tower does.

People like the traditional tower computer shape, unfortunately. A good design would have the hard drives in a separate enclosure to absorb the high pitched whine they usually generate with a different type of cooling design than the cpu and video card.

Have you actually looked at the G5/Pro enclosure? The hard drives and CD/DVD drive *are* in a separate enclosure, with separate air flow from the rest of the machine and its own set of fans and heat-sensing hardware so that the OS can independently control fan speed based on heat output. Same goes for the power supply. Same goes for the motherboard.

The cpu fan
produces a lower frequency of noise than the hard drives so the sound absorption used needs to be different.

Now you are talking about sound absorption, which is an unrelated topic. Break that out into another thread if you wish. I'll ignore it in this instance.

And the power supply should be
external as any power supply using positive cooling can adequately be cooled with a 120mm fan run on 5 volts, which is inaudible.

Oh that'd be really nice. Yet another box and cord I have to manage in back of my desk? No thanks. Remember: Apple doesn't do crappy design.

The Mac Pro, while still a lousy design for cooling, is much improved. At least they know better than to use sub 120mm fans. Check out the hard drive cooling. The first drive gets the fan, and the last drive cooks.

There are *many* things to consider when designing a case enclosure. Sometimes you have to make sacrifices. People who are good at managing all of the attributes and designing good cases are paid big bucks. If you think you can do better, design a prototype enclosure, make a trip to Cupertino, and present it to Apple. If your designs are good enough, and you show you're not just talking out of your ass and you really do know what you are talking about, I have no doubt in my mind Apple will snatch you up. ; )

I don't know why Apple is so short sighted in the cooling department. But they've been that way forever. How many hard drives were cooked in the G5 tower? Squashed up there in the corner.

The fact is the drives get adequate cooling. I have two drives in my G5 tower: a Maxtor 205GB 7200 rpm, and a Seagate 160GB 7200 rpm. I don't allow either one to sleep. The G5 keeps them at a constant 27˚ Celsius. That's just fine.

Has everyone forgot that heat rises?

Not when the heated air is constantly being drawn from front to back in an efficient manner, it doesn't.

JR

Message #19 - Posted 2007/04/21 - Adrian

The New Guy wrote:

How many hard drives
were cooked in the G5 tower? Squashed up there in the corner.

I'll guess ... eh, none? Come on all you other G5 Powermac owners, how many hard drives have you had fail due to heat problems?

Adrian

Message #20 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 11:46:17 -0500, Mike Rosenberg said:

Dave Balderstone wrote:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

I propose that it be used for cooking. Apple should start selling the iGrill, a device resembling a George Foreman grill, that connects to a Mac and uses its heat for cooking burgers and stuff.

I'd rather it be used to generate energy I can sell back to my electric company. : D

JR

Message #21 - Posted 2007/04/21 - Adrian

Jolly Roger wrote:

On 2007-04-21 11:46:17 -0500, Mike Rosenberg said:

Dave Balderstone wrote:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

I propose that it be used for cooking. Apple should start selling the iGrill, a device resembling a George Foreman grill, that connects to a Mac and uses its heat for cooking burgers and stuff.

I'd rather it be used to generate energy I can sell back to my electric company. : D

It does actually enable you to save some power on home heating so it reduces your bills ... if you had enough G5s running you wouldn't need any central heating at all! ;0

Adrian

Message #22 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 12:01:33 -0500, Adrian said:

The New Guy wrote:

How many hard drives
were cooked in the G5 tower? Squashed up there in the corner.

I'll guess ... eh, none? Come on all you other G5 Powermac owners, how many hard drives have you had fail due to heat problems?

Zero.

JR

Message #23 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 12:08:20 -0500, Adrian said:

Jolly Roger wrote:

On 2007-04-21 11:46:17 -0500, Mike Rosenberg said:

Dave Balderstone wrote:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

I propose that it be used for cooking. Apple should start selling the iGrill, a device resembling a George Foreman grill, that connects to a Mac and uses its heat for cooking burgers and stuff.

I'd rather it be used to generate energy I can sell back to my electric company. : D

It does actually enable you to save some power on home heating so it reduces your bills ... if you had enough G5s running you wouldn't need any central heating at all! ;0

That's true. My office has two G5 towers in it, and when both are in use it gets mighty toasty in here.

JR

Message #24 - Posted 2007/04/21 - Adrian

Jolly Roger wrote:

On 2007-04-21 12:01:33 -0500, Adrian said:

The New Guy wrote:

How many hard drives
were cooked in the G5 tower? Squashed up there in the corner.

I'll guess ... eh, none? Come on all you other G5 Powermac owners, how many hard drives have you had fail due to heat problems?

Zero.

And you have 2 G5 towers. My G5 tower has 2 hard drives ... both cool and healthy!

Anyone else? Come on, New Guy must have *somebody* who can back up his assertions.

Adrian

Message #25 - Posted 2007/04/21 - Dave Balderstone

Previously, Adrian wrote:

The New Guy wrote:

That is exactly what I'm talking about. Very bad cooling design. If you have hot air exiting, its not being cooled properly. The problem with so many case designs is they try to cool components with warmed interior case air. Which, when you think about it, is rather difficult. 9 fans....whatever for? How many heat generators are there in that box? CPU (which is liquid cooled in the G5 tower isn't it?), video card, hard drive(s), and to a very minor extent the ram, chipset and optical drive (when its working).

A good design would take exterior air to cool the heat generator and then immediately vent it out. Unfortunately, few designs do this.

You have some strange notions! Of course cool exterior air is used ... why the heck do you think the entire front of the G5/MacPro tower is perforated? It's so fresh cool air can be drawn in, used for cooling, and expelled out the back. The effectiveness of this system can easily be felt by placing your hand at the front where air goes in, and then at the back where the air comes out ... believe me there's no doubt that there is heat being removed! Where do you get the idea that it's using warmed interior air for cooling?

And my refrigerator uses cold interior air for cooling!

I am extraordinarily patient, provided I get my own way in the end. - Margaret Thatcher

Message #26 - Posted 2007/04/21 - The New Guy

How many hard drives were cooked in the G5 tower? Squashed up there in the corner.

I'll guess ... eh, none? Come on all you other G5 Powermac owners, how many hard drives have you had fail due to heat problems?

Zero.

And you have 2 G5 towers. My G5 tower has 2 hard drives ... both cool and healthy!

I wonder what the temperature of the hard drive really is? Do you have S.M.A.R.T or some other way of measuring temperatures? If a hard drive enclosure is designed well, the hard drive will barely be warm to the touch. Mounting a 120mm fan (running at 5 volts for inaudibility) directly under the hard drive (since the bottom gives off far more heat then the top) works wonders IF you're not using hot case air. Unfortunately that is rarely the case in most case designs. Hard drives are usually very warm to quite hot to the touch. That means their life span is drastically reduced.

Anyone else? Come on, New Guy must have *somebody* who can back up his assertions.

http://www.xlr8yourmac.com/G5/G5_drive_heat_tips.html "Well, here's the news: During the troubleshooting process, I began to notice that my drives were always very hot to the touch...extremely hot...burning hot. "
If a case is designed properly, you shouldn't even need fans to cool the hard drives; they would never get hot to the touch, just warm. But if you do use fans, the hard drives should be barely warm and often barely warm to the touch.

Googling
G5 overheating hard drives -imac
gives lots of examples.

If someone could find a good disassembly photo of the G5 tower I could make my points better. Here's one but its not so great: http://flickr.com/photo_zoom.gne?id=322407878&size=l But you can see that when the side cover is on its pretty hard for the fans to suck the air out of that tiny hard drive space being the hard drive supports are going to block a lot of air movement. And that, apparently, is the reason Apple had to do so many 250mb Sata hard drive warranty replacements. But common sense says you don't cram heat generating devices together in a tiny space.

This photo shows how crammed together the hard drives would be if one used 2. Very little room to "breathe".
http://flickr.com/photo_zoom.gne?id=21172866&size=l

Here is a better view showing that the problem compounds mightily when 2 hard drives are used.
http://flickr.com/photo_zoom.gne?id=143336885&size=l When 1 is used you get far more airflow. A thinking person of course, would mount the hard drive upside down (as it produces far more heat) and on the bottom to allow the heat to rise and disperse. Probably why the Mac Pro mounts their drives upside down now. Or should it be referred to as right side up?

Message #27 - Posted 2007/04/21 - The New Guy

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place! In cooling, first the heat sink absorbs the initial heat, then air cools the heat sink. If the heat sink is raging hot, its a lousy heat sink. Read about the Scythe Ninja for an example of good design.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

Message #28 - Posted 2007/04/21 - The New Guy

That is exactly what I'm talking about. Very bad cooling design. If you have hot air exiting, its not being cooled properly. The problem with so many case designs is they try to cool components with warmed interior case air. Which, when you think about it, is rather difficult. 9 fans....whatever for? How many heat generators are there in that box? CPU (which is liquid cooled in the G5 tower isn't it?), video card, hard drive(s), and to a very minor extent the ram, chipset and optical drive (when its working).

A good design would take exterior air to cool the heat generator and then immediately vent it out. Unfortunately, few designs do this.

You have some strange notions! Of course cool exterior air is used ... why the heck do you think the entire front of the G5/MacPro tower is perforated? It's so fresh cool air can be drawn in, used for cooling, and expelled out the back. The effectiveness of this system can easily be felt by placing your hand at the front where air goes in, and then at the back where the air comes out ... believe me there's no doubt that there is heat being removed! Where do you get the idea that it's using warmed interior air for cooling?

OK - tell me if the video card is being cooled with interior case air? And the ram and the chipset?
And the hard drives?
The perforations are hardly useful if one crams the enclosure with 2 hard drives. One hard drive is no problem. I should have added that in my initial posting.
Measure the interior temperature of a computer. That spells it out. Properly set up it should be barely above a warm room. Because as soon as something heats up, that heated air is vented immediately.

Message #29 - Posted 2007/04/21 - G.T.

The New Guy wrote:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place! In cooling, first the heat sink absorbs the initial heat, then air cools the heat sink. If the heat sink is raging hot, its a lousy heat sink. Read about the Scythe Ninja for an example of good design.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

If you want to be taken seriously you need to take a course in thermodynamics. If you take one, you'll see the error of your ways. Heat doesn't magically disappear. A "properly designed heat sink" will have heat spread over a greater surface but if the method for removing that heat from the computer is to blow it out the case the air coming out of the case is still going to be the same temperature.

Greg

The ticketbastard Tax Tracker:
http://www.ticketmastersucks.org/tracker.html

Dethink to survive - Mclusky

Message #30 - Posted 2007/04/21 - Adrian

The New Guy wrote:

I wonder what the temperature of the hard drive really is?

Unlike you, I don't need to speculate. Yes my drives have SMART sensors. They've been working away all day ... my Mac is poorly located in a warm room and next to a central heating radiator ... sorry about that ... the current temperature of main drive (there are 2 in there) is 40c.

Adrian

Message #31 - Posted 2007/04/21 - Dave Balderstone

Previously, G.T. wrote:

The New Guy wrote:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place! In cooling, first the heat sink absorbs the initial heat, then air cools the heat sink. If the heat sink is raging hot, its a lousy heat sink. Read about the Scythe Ninja for an example of good design.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

If you want to be taken seriously you need to take a course in thermodynamics. If you take one, you'll see the error of your ways. Heat doesn't magically disappear. A "properly designed heat sink" will have heat spread over a greater surface but if the method for removing that heat from the computer is to blow it out the case the air coming out of the case is still going to be the same temperature.

He wants a room temperature superconductor.

I am extraordinarily patient, provided I get my own way in the end. - Margaret Thatcher

Message #32 - Posted 2007/04/21 - Adrian

The New Guy wrote:

If a case is designed properly, you shouldn't even need fans to cool the hard drives; they would never get hot to the touch, just warm. But if you do use fans, the hard drives should be barely warm and often barely warm to the touch.

The fans only run if the drives get especially hot. The drives are indeed barely warm to the touch.

Adrian

Message #33 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 13:56:44 -0500, The New Guy said:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place!

Components like RAM, hard drives, CPUs generate heat. That's a fact of life. Of *course* the components will get hot in the first place. You really should think about what you are saying.

In cooling, first the heat
sink absorbs the initial heat, then air cools the heat sink.

The G5 and Mac Pro CPU heat sinks *do* absorb the heat generated by the CPUs, and the G5's CPU cooling compartment *does* ensure a steady flow of cool air enters from the front grill of the computer case, passes directly over the heat sink absorbing the heat from the heat sink (thereby cooling the heat sink and equally warming the air), and the warm air exits promptly out the back grill of the case. The warmer the air exiting the case, the better job the G5/Pro is doing of cooling the CPUs.

In the G5 DIMM RAM chips don't have heat sinks. So the cool air entering from the front grill off the case cools them. They are directly in front of the front grill, so they get the coolest air.

If the heat sink is raging hot, its a lousy heat sink.

The heat sink in my G5 tower is not hot at all when running. Thee air coming out the back is rather warm though. This is an indication that the cooling system is doing its job well.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

You are contradicting yourself. Earlier you said this:

If you have hot air exiting, its not being cooled properly.

Yet now you are seemingly agreeing the air coming out of the back of the case *should* be hot.

Which is it? (Don't bother answering - those of us who are knowledgeable about thermodynamics know the hotter the air coming out, the better job the cooling system is doing.)

JR

Message #34 - Posted 2007/04/21 - The New Guy

That just seems like really bad cooling! But cooling was never Apple's strong point. I wonder if its possible to replace the cpu heat sink with something better?

Have you seen inside a Powermac G5? All metal fully perforated design, liquid cooling radiators and fans on both processors ... 9 fans in the case ... it heats my room quite nicely!

That is exactly what I'm talking about. Very bad cooling design. If you have hot air exiting, its not being cooled properly.

The idea of any cooling system is to displace the heat - in other words, move the heat from one undesirable place to another more desirable place. I would say the fact that the G5/Pro displaces as much heat as it does shows that it is in fact doing a *great* job at cooling the components of the G5/Pro. Do you actually propose that heat should stay *inside* the machine? Or are you saying the fact that the components generate heat to begin with somehow equates to bad cooling?

)

As mentioned before, if the heat exiting is hot, the heat sink is not performing well. Read about fanless CPU heat sinks. They are so well engineered that when you run a 120/140mm fan at 5 volts (instead of the audible 12 volts) they both cool the heat sink effortlessly but are utterly inaudible. THAT is good design.

The problem
with so many case designs is they try to cool components with warmed interior case air.

This is precisely what the G5/Pro cooling system does *not* do. It is designed to move cooler air from the outside of the machine (in front of it) through the front vent, across all heat-generating components, and right out the back, and in a very efficient manner. It's pretty much a straight line from front to back. That's why it displaces as much heat as it does.

The trouble is its a lot easier moving hot air vertically, then horizontally.

Which, when you think about it, is rather difficult. 9 fans....whatever for?

To ensure there is enough constant air flow to displace heat in an efficient manner. Why else?

One cpu fan (2 for dual processors), maybe a video card fan, and a power supply fan. In a good design, the heat from the hard drives, ram, chipset and optical drive just vents up and out. No horizontal obstacles in the way. You'll notice the Mac Pro doesn't have so many fans. 9 fans is absurd. What a racket. They are smaller (they look like 80mm) so they often use 2 together. 1 140mm is far superior to 2 x 80mm. And WAY quieter. Actually inaudible almost all the time.

How many heat generators are
there in that box? CPU (which is liquid cooled in the G5 tower isn't it?), video card, hard drive(s), and to a very minor extent the ram, chipset and optical drive (when its working).

You forgot the power supply.

I mentioned the power supply. External, throw it on the floor, with a 5 volt fan that is inaudible. The power supply should never be part of the computer case. The external idea that the Mac Mini uses is brilliant. Hope that catches on all over the industry.

And the power supply should be
external as any power supply using positive cooling can adequately be cooled with a 120mm fan run on 5 volts, which is inaudible.

Oh that'd be really nice. Yet another box and cord I have to manage in back of my desk? No thanks. Remember: Apple doesn't do crappy design.

Here we have a typical reaction: a new concept hits a closed mind. "If it works better not in the case, it shouldn't be in the case." I'm sure you can "manage" a box on the floor somewhere. :) If its on the floor out of the way, that there is nothing to manage. Like the Mac Mini.

The Mac Pro, while still a lousy design for cooling, is much improved. At least they know better than to use sub 120mm fans. Check out the hard drive cooling. The first drive gets the fan, and the last drive cooks.

There are *many* things to consider when designing a case enclosure. Sometimes you have to make sacrifices. People who are good at managing all of the attributes and designing good cases are paid big bucks. If you think you can do better, design a prototype enclosure, make a trip to Cupertino, and present it to Apple. If your designs are good enough, and you show you're not just talking out of your ass and you really do know what you are talking about, I have no doubt in my mind Apple will snatch you up. ; )

I'm starting to walk in that direction now! :)

I don't know why Apple is so short sighted in the cooling department. But they've been that way forever. How many hard drives were cooked in the G5 tower? Squashed up there in the corner.

The fact is the drives get adequate cooling. I have two drives in my G5 tower: a Maxtor 205GB 7200 rpm, and a Seagate 160GB 7200 rpm. I don't allow either one to sleep. The G5 keeps them at a constant 27˚ Celsius. That's just fine.

That temperature sounds good. But its probably not accurate. Is that the interior temperature or the ambient temperature in the hard drive area? I think the interior hard drive temperature is the one to watch.

Message #35 - Posted 2007/04/21 - The New Guy

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place! In cooling, first the heat sink absorbs the initial heat, then air cools the heat sink. If the heat sink is raging hot, its a lousy heat sink. Read about the Scythe Ninja for an example of good design.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

If you want to be taken seriously you need to take a course in thermodynamics. If you take one, you'll see the error of your ways. Heat doesn't magically disappear. A "properly designed heat sink" will have heat spread over a greater surface but if the method for removing that heat from the computer is to blow it out the case the air coming out of the case is still going to be the same temperature.

Well, with my system the warmed air ain't very warm! If your heat sink is working well, the heat is dissipated over a large area of the fins. So the heat sink never gets hot. If the heat sink doesn't get hot, the air doesn't get hot.

Message #36 - Posted 2007/04/21 - G.T.

The New Guy wrote:

As mentioned before, if the heat exiting is hot, the heat sink is not performing well. Read about fanless CPU heat sinks. They are so well engineered that when you run a 120/140mm fan at 5 volts (instead of the audible 12 volts) they both cool the heat sink effortlessly but are utterly inaudible. THAT is good design.

Please stop polluting Usenet with your idiocy.

Greg

The ticketbastard Tax Tracker:
http://www.ticketmastersucks.org/tracker.html

Dethink to survive - Mclusky

Message #37 - Posted 2007/04/21 - The New Guy

I wonder what the temperature of the hard drive really is?

Unlike you, I don't need to speculate. Yes my drives have SMART sensors. They've been working away all day ... my Mac is poorly located in a warm room and next to a central heating radiator ... sorry about that ... the current temperature of main drive (there are 2 in there) is 40c.

Do you find the temperature of the 2 drives quite similar? I guess that would depend on the workload of course. Can a user opt to run 2 Sata drives in the G5 tower in Raid 0? Then they would have identical workloads.

Message #38 - Posted 2007/04/21 - The New Guy

If a case is designed properly, you shouldn't even need fans to cool the hard drives; they would never get hot to the touch, just warm. But if you do use fans, the hard drives should be barely warm and often barely warm to the touch.

The fans only run if the drives get especially hot. The drives are indeed barely warm to the touch.

Well then your system is working well. Too bad those other people didn't fare so well. Maybe the heat sensor that controlled the hard drive fans was a little off.

Message #39 - Posted 2007/04/21 - The New Guy

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place!

Components like RAM, hard drives, CPUs generate heat. That's a fact of life. Of *course* the components will get hot in the first place. You really should think about what you are saying.

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense. Regarding ram, you'll notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

In cooling, first the heat
sink absorbs the initial heat, then air cools the heat sink.

The G5 and Mac Pro CPU heat sinks *do* absorb the heat generated by the CPUs, and the G5's CPU cooling compartment *does* ensure a steady flow of cool air enters from the front grill of the computer case, passes directly over the heat sink absorbing the heat from the heat sink (thereby cooling the heat sink and equally warming the air), and the warm air exits promptly out the back grill of the case. The warmer the air exiting the case, the better job the G5/Pro is doing of cooling the CPUs.

Did all the G5 towers use water cooling or just some of them?

In the G5 DIMM RAM chips don't have heat sinks. So the cool air entering from the front grill off the case cools them. They are directly in front of the front grill, so they get the coolest air.

If the heat sink is raging hot, its a lousy heat sink.

The heat sink in my G5 tower is not hot at all when running. Thee air coming out the back is rather warm though. This is an indication that the cooling system is doing its job well.

Yes, that sounds right.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

You are contradicting yourself. Earlier you said this:

If you have hot air exiting, its not being cooled properly.

Yet now you are seemingly agreeing the air coming out of the back of the case *should* be hot.
Which is it? (Don't bother answering - those of us who are knowledgeable about thermodynamics know the hotter the air coming out, the better job the cooling system is doing.)

To clarify, a good heat sink won't get hot. So the air won't get hot. But of course it will get warm. And that warmed air needs to be vented immediately. Hope that makes sense.

If anyone has found some good interior pictures of the G5 tower, please post them. Especially with the CPU covers off. I can't remember what's under them.

Message #40 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 14:00:38 -0500, The New Guy said:

OK - tell me if the video card is being cooled with interior case air?

Nope it's not cooled by interior case air.

The beauty of the design of the G5/Pro is that the video card/PCI/AGP card section is separate from other parts of the computer. That section has its own air flow and its own fans and temperature sensors. The grills on the front and back of the case have so many holes that air moves quite freely through the grill. The numerous fans ensure that the air flowing into the front and out the back is constant.

The result is the video card is being cooled by a steady stream of cool air from in front of the case.

And the ram and the chipset?

Again, this is another separate section with its own air flow and its own fans and temperature sensors. Because of the open grill design, air flow is unimpeded from the outside front of the case, through the CPU heat sink, out the back of the case. This is why the air exiting is as warm as it is - that warmth is being efficiently transferred out of the computer.

And the hard drives?

This is yet another separate section with its own air flow and its own fans and temperature sensors. Because of the open grill design, air flow is unimpeded from the outside front of the case, over the tops and bottoms (and sides) of each hard drive, out the back of the case. What little heat is able to spread upwards from the bottom drive to the top drive is minimal.

As I said else-thread, I have two 7200 RPM drives in my G5 and a constant temperature of around 27˚ Celsius is maintained.

The perforations are hardly useful if one crams the enclosure with 2 hard drives.

Wrong. The air flowing between and around the hard drives is anything but minimal. It's quite sufficient to keep them cool, as evidenced by the temperature of my hard drives, which both stay running 24/7 and are constantly kept at a relatively cool 27˚ Celsius.

One hard drive is no problem. I should have added that in my initial posting.

Neither are *two* hard drives!

Measure the interior temperature of a computer. That spells it out.

Okay - since you insist... I happen to have a portable Radio Shack digital thermometer handy. : )

Note: I'll have to rest the sensor end of the wire on the bare metal floor of some compartments, but hopefully it won't pick up too much heat from the metal. We'll just say the temperature readings could be off by +/- a couple degrees. ; )

In each measurement, I'll place the sensor with preference to placements where the sensor is dangling freely in the ambient air of the compartment, will completely close the case up again, and will wait 5 minutes for the temperature reading to settle.

Ambient office temperature: 77.6˚ F

Inside G5 tower (from top to bottom):

• CD/DVD/Hard drive section (front): 80.5˚ F • CD/DVD/Hard drive section (rear): 88.7˚ F

Difference: 8.2˚ F

• PCI/AGP/video card section (front): 80.4˚ F • PCI/AGP/video card section (rear): 85.2˚ F

Difference: 4.8˚ F

• RAM/CPU section (front): 79.1˚ F
• RAM/CPU section (rear): 88.3˚ F

Difference: 9.2˚ F

Since the air is constantly moving from front to back in an efficient manner, there is a wide difference between the temperature in the front of the case and the temperature in the back of the case, as you would expect with a constant, efficient air flow. If the air inside the case were stagnant, as you seem to keep suggesting, this difference would not be nearly as significant.

As far as your hypothesis that much of the heat is rising towards the top of the case rather than going straight out the back in an efficient manner, here is a recap of the difference in ambient front temperatures:

• CD/DVD/Hard drive section (front): 80.5˚ F • PCI/AGP/video card section (front): 80.4˚ F • RAM/CPU section (front): 79.1˚ F

So total bottom-to-top ambient internal temperature difference is a minimal 1.4˚ F.

JR

Message #41 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 16:27:56 -0500, The New Guy said:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place! In cooling, first the heat sink absorbs the initial heat, then air cools the heat sink. If the heat sink is raging hot, its a lousy heat sink. Read about the Scythe Ninja for an example of good design.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

If you want to be taken seriously you need to take a course in thermodynamics. If you take one, you'll see the error of your ways. Heat doesn't magically disappear. A "properly designed heat sink" will have heat spread over a greater surface but if the method for removing that heat from the computer is to blow it out the case the air coming out of the case is still going to be the same temperature.

Well, with my system the warmed air ain't very warm! If your heat sink is working well, the heat is dissipated over a large area of the fins. So the heat sink never gets hot. If the heat sink doesn't get hot, the air doesn't get hot.

Faulty logic at it's best.

JR

Message #42 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 16:36:40 -0500, The New Guy said:

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place!

Components like RAM, hard drives, CPUs generate heat. That's a fact of life. Of *course* the components will get hot in the first place. You really should think about what you are saying.

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense.

No - you are missing basic concepts here. Heat doesn't magically disappear. It must go somewhere, and a well-designed cooling system will move the heat outside of the unit. The greater the difference between the incoming air and the outgoing air, the better job the cooling system is doing.

Regarding ram, you'll
notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

They have heat sinks because the components get hotter than previous RAM chips did, and air flow over the chip surface, by itself, isn't enough. The heat sinks provide more area for air to come into contact with, allowing for more efficient cooling.

In cooling, first the heat

sink absorbs the initial heat, then air cools the heat sink.

The G5 and Mac Pro CPU heat sinks *do* absorb the heat generated by the CPUs, and the G5's CPU cooling compartment *does* ensure a steady flow of cool air enters from the front grill of the computer case, passes directly over the heat sink absorbing the heat from the heat sink (thereby cooling the heat sink and equally warming the air), and the warm air exits promptly out the back grill of the case. The warmer the air exiting the case, the better job the G5/Pro is doing of cooling the CPUs.

Did all the G5 towers use water cooling or just some of them?

Only the fastest 2.5GHz model had liquid cooling. All other models had standard air cooling.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

You are contradicting yourself. Earlier you said this:

If you have hot air exiting, its not being cooled properly.

Yet now you are seemingly agreeing the air coming out of the back of the case *should* be hot.
Which is it? (Don't bother answering - those of us who are knowledgeable about thermodynamics know the hotter the air coming out, the better job the cooling system is doing.)

To clarify, a good heat sink won't get hot. So the air won't get hot. But of course it will get warm. And that warmed air needs to be vented immediately. Hope that makes sense.

The air *is* expelled immediately, due to the design of the case. See:

<http://www.adcom.bg/Web/Apple/Apple_files/designcooling06232003.jpg>

If anyone has found some good interior pictures of the G5 tower, please post them. Especially with the CPU covers off. I can't remember what's under them.

Just massive heat sinks:

<http://www.sharpeningbeneath.com/g5guide/>

JR

Message #43 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 16:20:02 -0500, The New Guy said:

As mentioned before, if the heat exiting is hot, the heat sink is not performing well.

You're just wrong. I'm only going to say this once more:

The idea of any cooling system is to displace the heat - in other words, move the heat from one undesirable place to another more desirable place. Energy (heat) doesn't magically appear and disappear - it must go *somewhere*. The fact that the air coming out is hot is *proof* that the cooling system is working efficiently.

Read about fanless CPU heat sinks.

Only after *you* read about thermodynamics. You're talking out of your ass. Sorry to use such foul language, but it's truly appropriate in this instance.

JR

Message #44 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 16:20:02 -0500, The New Guy said:

The problem
with so many case designs is they try to cool components with warmed interior case air.

This is precisely what the G5/Pro cooling system does *not* do. It is designed to move cooler air from the outside of the machine (in front of it) through the front vent, across all heat-generating components, and right out the back, and in a very efficient manner. It's pretty much a straight line from front to back. That's why it displaces as much heat as it does.

The trouble is its a lot easier moving hot air vertically, then horizontally.

Yet, in the case of Apple's G5/Pro cases, Apple has managed to move more hot air horizontally than vertically.

JR

Message #45 - Posted 2007/04/21 - Jolly Roger

On 2007-04-21 16:20:02 -0500, The New Guy said:

One cpu fan (2 for dual processors), maybe a video card fan, and a power supply fan. In a good design, the heat from the hard drives, ram, chipset and optical drive just vents up and out. No horizontal obstacles in the way. You'll notice the Mac Pro doesn't have so many fans. 9 fans is absurd. What a racket.

First, my Dell and other PCs are louder than this G5. It's simply not that loud.

Second, stop changing the subject. We are talking about efficiency of cooling, not how loud fans are.

JR

Message #46 - Posted 2007/04/21 - Adrian

Jolly Roger wrote:

As I said else-thread, I have two 7200 RPM drives in my G5 and a constant temperature of around 27˚ Celsius is maintained.

I find a similar temperature in the drive bay. However, the SMART sensors within the drives which are reported by my Temperature Monitor Dashboard widget show 40 to 41 degrees Celsius ... which is still within normal operating temperature range.

Adrian

Message #47 - Posted 2007/04/21 - Adrian

The New Guy wrote:

Do you find the temperature of the 2 drives quite similar? I guess that would depend on the workload of course. Can a user opt to run 2 Sata drives in the G5 tower in Raid 0? Then they would have identical workloads.

Both drives within a degree. I haven't experimented with RAID but some people do that. I believe.

Adrian

Message #48 - Posted 2007/04/21 - Adrian

The New Guy wrote:

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense. Regarding ram, you'll notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

Yes but it doesn't matter how big, small, efficient or inefficient the heat sink is ... there is still the same total amount of heat to be dissipated. A better heat sink simply spreads it around a larger area, reducing the hot spot on the component in the process. So good heat sinks are heplful in moving heat away from one spot and thereby protecting the component. However, the total amount of heat produced and the amount which has to come out of the back or top of the vented case will be the same.

Adrian

Message #49 - Posted 2007/04/22 - Jolly Roger

On 2007-04-21 17:36:52 -0500, Adrian said:

Jolly Roger wrote:

As I said else-thread, I have two 7200 RPM drives in my G5 and a constant temperature of around 27˚ Celsius is maintained.

I find a similar temperature in the drive bay. However, the SMART sensors within the drives which are reported by my Temperature Monitor Dashboard widget show 40 to 41 degrees Celsius ... which is still within normal operating temperature range.

Same here - between 37˚ C and 39˚ C:

# /usr/local/sbin/smartctl -A /dev/disk0 | grep -i Temp

194 Temperature_Celsius 0x0032 039

# /usr/local/sbin/smartctl -A /dev/disk1 | grep -i Temp

194 Temperature_Celsius 0x0022 037

JR

Message #50 - Posted 2007/04/22 - The New Guy

Previously, Jolly Roger wrote:

On 2007-04-21 14:00:38 -0500, The New Guy said:

OK - tell me if the video card is being cooled with interior case air?

Nope it's not cooled by interior case air.

The beauty of the design of the G5/Pro is that the video card/PCI/AGP card section is separate from other parts of the computer. That section has its own air flow and its own fans and temperature sensors. The grills on the front and back of the case have so many holes that air moves quite freely through the grill. The numerous fans ensure that the air flowing into the front and out the back is constant.

The result is the video card is being cooled by a steady stream of cool air from in front of the case.

And the ram and the chipset?

Again, this is another separate section with its own air flow and its own fans and temperature sensors. Because of the open grill design, air flow is unimpeded from the outside front of the case, through the CPU heat sink, out the back of the case. This is why the air exiting is as warm as it is - that warmth is being efficiently transferred out of the computer.

And the hard drives?

This is yet another separate section with its own air flow and its own fans and temperature sensors. Because of the open grill design, air flow is unimpeded from the outside front of the case, over the tops and bottoms (and sides) of each hard drive, out the back of the case. What little heat is able to spread upwards from the bottom drive to the top drive is minimal.

As I said else-thread, I have two 7200 RPM drives in my G5 and a constant temperature of around 27˚ Celsius is maintained.

The perforations are hardly useful if one crams the enclosure with 2 hard drives.

Wrong. The air flowing between and around the hard drives is anything but minimal. It's quite sufficient to keep them cool, as evidenced by the temperature of my hard drives, which both stay running 24/7 and are constantly kept at a relatively cool 27˚ Celsius.

One hard drive is no problem. I should have added that in my initial posting.

Neither are *two* hard drives!

Measure the interior temperature of a computer. That spells it out.

Okay - since you insist... I happen to have a portable Radio Shack digital thermometer handy. : )

Note: I'll have to rest the sensor end of the wire on the bare metal floor of some compartments, but hopefully it won't pick up too much heat from the metal. We'll just say the temperature readings could be off by +/- a couple degrees. ; )

In each measurement, I'll place the sensor with preference to placements where the sensor is dangling freely in the ambient air of the compartment, will completely close the case up again, and will wait 5 minutes for the temperature reading to settle.

Ambient office temperature: 77.6˚ F

Inside G5 tower (from top to bottom):

• CD/DVD/Hard drive section (front): 80.5˚ F • CD/DVD/Hard drive section (rear): 88.7˚ F

Difference: 8.2˚ F

• PCI/AGP/video card section (front): 80.4˚ F • PCI/AGP/video card section (rear): 85.2˚ F

Difference: 4.8˚ F

• RAM/CPU section (front): 79.1˚ F
• RAM/CPU section (rear): 88.3˚ F

Difference: 9.2˚ F

Since the air is constantly moving from front to back in an efficient manner, there is a wide difference between the temperature in the front of the case and the temperature in the back of the case, as you would expect with a constant, efficient air flow. If the air inside the case were stagnant, as you seem to keep suggesting, this difference would not be nearly as significant.

As far as your hypothesis that much of the heat is rising towards the top of the case rather than going straight out the back in an efficient manner, here is a recap of the difference in ambient front temperatures:

• CD/DVD/Hard drive section (front): 80.5˚ F • PCI/AGP/video card section (front): 80.4˚ F • RAM/CPU section (front): 79.1˚ F

So total bottom-to-top ambient internal temperature difference is a minimal 1.4˚ F.

You are very thorough. I'm curious: when you put the side panel on, does it touch the section divisions? Or would air from the motherboard make its way up to the hard drive area?

Message #51 - Posted 2007/04/22 - Jolly Roger

On 2007-04-21 20:30:04 -0500, The New Guy said:

I'm curious: when you put the side panel on, does it touch the section divisions? Or would air from the motherboard make its way up to the hard drive area?

Under normal circumstances, there's a hairline crack of space between the clear side panel and the dividers. So I don't see much air going that route when the front and back grills offer barely any resistance at all to the flow.

For my temperature tests, the wire of the sensor is about a millimeter thick, so the opening was also minimal, and I was actually about to put *both* side panels on during the tests.

JR

Message #52 - Posted 2007/04/22 - The New Guy

If you have hot air exiting, its not being cooled properly.

So where do you propose the heat actually go?

It shouldn't be hot in the first place!

Components like RAM, hard drives, CPUs generate heat. That's a fact of life. Of *course* the components will get hot in the first place. You really should think about what you are saying.

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense.

No - you are missing basic concepts here. Heat doesn't magically disappear. It must go somewhere, and a well-designed cooling system will move the heat outside of the unit. The greater the difference between the incoming air and the outgoing air, the better job the cooling system is doing.

Devices that run very hot need larger heat sinks. If you put a huge heat sink on a device, that heat sink won't get very hot. So the air around it won't get very not. That is the basic concept of a heat sink. If the heat sink is getting hot, its too small or more correctly, it doesn't have enough radiating surface to disperse the heat. So it gets hot. So the air around it gets hot. Well designed heat sinks are huge. Some won't even fit in some average sized cases. But because of their size, some cool adequately without even a fan. A larger (120 mm or larger) fan run at 5 volts in inaudible so its illogical not to use it. Then you have superb, silent cooling. And of course you want to vent that warmed air outside right away.

Regarding ram, you'll
notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

They have heat sinks because the components get hotter than previous RAM chips did, and air flow over the chip surface, by itself, isn't enough. The heat sinks provide more area for air to come into contact with, allowing for more efficient cooling.

Glad we're on the same page there.

In cooling, first the heat

sink absorbs the initial heat, then air cools the heat sink.

The G5 and Mac Pro CPU heat sinks *do* absorb the heat generated by the CPUs, and the G5's CPU cooling compartment *does* ensure a steady flow of cool air enters from the front grill of the computer case, passes directly over the heat sink absorbing the heat from the heat sink (thereby cooling the heat sink and equally warming the air), and the warm air exits promptly out the back grill of the case. The warmer the air exiting the case, the better job the G5/Pro is doing of cooling the CPUs.

Did all the G5 towers use water cooling or just some of them?

Only the fastest 2.5GHz model had liquid cooling. All other models had standard air cooling.

Ah - ok. So I need to source out more interior photos of the sub 2.5 ghz models.

A good design would take exterior air to cool the heat generator and then immediately vent it out.

As hot air, exiting the case? You've said that's not proper.

A properly designed heat sink would not get very hot. The warmed air would be immediately vented out. (Since its stupid to try to cool something with hot air.)

You are contradicting yourself. Earlier you said this:

If you have hot air exiting, its not being cooled properly.

Yet now you are seemingly agreeing the air coming out of the back of the case *should* be hot.
Which is it? (Don't bother answering - those of us who are knowledgeable about thermodynamics know the hotter the air coming out, the better job the cooling system is doing.)

To clarify, a good heat sink won't get hot. So the air won't get hot. But of course it will get warm. And that warmed air needs to be vented immediately. Hope that makes sense.

The air *is* expelled immediately, due to the design of the case. See:

<http://www.adcom.bg/Web/Apple/Apple_files/designcooling06232003.jpg>

Its hard to tell, but in that image it looks like the air to the CPU heat sinks first passes over the ram. And the air to the hard drives first passes over the optical drive(s).

If anyone has found some good interior pictures of the G5 tower, please post them. Especially with the CPU covers off. I can't remember what's under them.

Just massive heat sinks:

<http://www.sharpeningbeneath.com/g5guide/>

Message #53 - Posted 2007/04/22 - The New Guy

Previously, Adrian wrote:

The New Guy wrote:

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense. Regarding ram, you'll notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

Yes but it doesn't matter how big, small, efficient or inefficient the heat sink is ... there is still the same total amount of heat to be dissipated. A better heat sink simply spreads it around a larger area, reducing the hot spot on the component in the process. So good heat sinks are heplful in moving heat away from one spot and thereby protecting the component. However, the total amount of heat produced and the amount which has to come out of the back or top of the vented case will be the same.

This is pointless. I give up. You people just don't understand heat sinks. Think of this....if you put an immense heat sink on a old video card, it may not even get warm. That's because the heat sink is up to the task. Now if the heat sink doesn't get warm, then air around it doesn't get warm. I don't understand why this concept is so difficult to grasp.

The worse the heat sink, the more air it needs flushed through it to cool it. And the hotter that air is going to be.

Message #54 - Posted 2007/04/22 - The New Guy

Previously, Jolly Roger wrote:

On 2007-04-21 20:30:04 -0500, The New Guy said:

I'm curious: when you put the side panel on, does it touch the section divisions? Or would air from the motherboard make its way up to the hard drive area?

Under normal circumstances, there's a hairline crack of space between the clear side panel and the dividers. So I don't see much air going that route when the front and back grills offer barely any resistance at all to the flow.

For my temperature tests, the wire of the sensor is about a millimeter thick, so the opening was also minimal, and I was actually about to put *both* side panels on during the tests.

When you took the temperature tests, was the side panel on, as per normal operation?

Message #55 - Posted 2007/04/22 - The New Guy

Previously, Adrian wrote:

Jolly Roger wrote:

As I said else-thread, I have two 7200 RPM drives in my G5 and a constant temperature of around 27˚ Celsius is maintained.

I find a similar temperature in the drive bay. However, the SMART sensors within the drives which are reported by my Temperature Monitor Dashboard widget show 40 to 41 degrees Celsius ... which is still within normal operating temperature range.

And since the sensor is inside the drive, you have the side panel on, per normal operation?

Message #56 - Posted 2007/04/22 - The New Guy

Previously, Adrian wrote:

The New Guy wrote:

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense. Regarding ram, you'll notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

Yes but it doesn't matter how big, small, efficient or inefficient the heat sink is ... there is still the same total amount of heat to be dissipated. A better heat sink simply spreads it around a larger area, reducing the hot spot on the component in the process. So good heat sinks are heplful in moving heat away from one spot and thereby protecting the component. However, the total amount of heat produced and the amount which has to come out of the back or top of the vented case will be the same.

That's true, yes. But every case has a certain amount of airflow. A well designed heat sink will require less airflow to stay cool. Thermodynamic theories are easy to apply if there is zero airflow. Thankfully, in this situation, there is airflow.

Message #57 - Posted 2007/04/22 - The New Guy

As I said else-thread, I have two 7200 RPM drives in my G5 and a constant temperature of around 27˚ Celsius is maintained.

I find a similar temperature in the drive bay. However, the SMART sensors within the drives which are reported by my Temperature Monitor Dashboard widget show 40 to 41 degrees Celsius ... which is still within normal operating temperature range.

And the OS is on one hard drive so that hard drive is used far more than the other? Or are they hooked up in Raid 0 so they are used all the time equally?

Message #58 - Posted 2007/04/22 - Eric Lindsay

Previously, The New Guy wrote:

I don't know why Apple is so short sighted in the cooling department. But they've been that way forever.

At least part of the problem was IBM had a lot of trouble with the G5, with poor yields of the faster versions. That usually means even greater than normal heat issues. Apple ended up using an expensive third party automotive cooling system for their fastest PowerMacs. I don't know how much the PowerMac power supplies were pulling, but they needed a UPS that had more capacity than the 600VA on hand.

Regarding the 20" iMac G5, my second generation ALS model 2GHz CPU runs at around 54C all the time, and the 400 GB hard drive at 53C. Ambient mid afternoon temperature is 29C, and those conditions (and a half dozen apps running) push the fans just above their low settings. The hard drive fan is at 3100 rpm, instead of the normal 2300. The only time I push the three fans into full is ripping DVDs or rendering. Fans are ramping up usually well before the CPU hits the 75C point that indicates it is just too hot.

One thing to check on an iMac G5 is that you clean the grill at the bottom of the case say twice a year. This collects a dust build up that makes a real difference to temperature and cooling. I probably should open the case and dust the interior, given I have had the iMac for two years.

The other problem Apple have is the one they make for themselves. If they solve all the cooling problems for a given size case, and the power consumption of the chips drop, they end up designing a smaller, neater case, and promptly run hot again. The iMac G5 after mine was a smaller case. They used the same case for the Intel design, and I am certain that ran at least 10C cooler. I very strongly suspect that soon after Santa Rosa chips appear, Apple will put them into an even smaller iMac case, and the temperature will go up again.

Second generation Macs seem like a good idea to me.

Message #59 - Posted 2007/04/22 - Jolly Roger

On 2007-04-21 22:20:49 -0500, The New Guy said:

The air *is* expelled immediately, due to the design of the case. See:

<http://www.adcom.bg/Web/Apple/Apple_files/designcooling06232003.jpg>

Its hard to tell, but in that image it looks like the air to the CPU heat sinks first passes over the ram. And the air to the hard drives first passes over the optical drive(s).

This is the G5 tower, and the RAM DIMM chips the G5 uses don't get very warm at all. Also, most of the tim the optical drive isn't even in use and is not generating heat.

The design of the Pro case is a bit different, and the RAM (it does get much warmer) is not in the same location,

JR

Message #60 - Posted 2007/04/22 - Jolly Roger

On 2007-04-21 22:27:13 -0500, The New Guy said:

Previously, Adrian wrote:

The New Guy wrote:

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense. Regarding ram, you'll notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

Yes but it doesn't matter how big, small, efficient or inefficient the heat sink is ... there is still the same total amount of heat to be dissipated. A better heat sink simply spreads it around a larger area, reducing the hot spot on the component in the process. So good heat sinks are heplful in moving heat away from one spot and thereby protecting the component. However, the total amount of heat produced and the amount which has to come out of the back or top of the vented case will be the same.

This is pointless. I give up. You people just don't understand heat sinks. Think of this....if you put an immense heat sink on a old video card, it may not even get warm. That's because the heat sink is up to the task. Now if the heat sink doesn't get warm, then air around it doesn't get warm. I don't understand why this concept is so difficult to grasp.

Yes, I'm getting tired of repeating myself as well. : )

As I've said numerous times before, the heat doesn't just go away magically because the heat sink is larger. Heat must go somewhere, and it goes into the air flowing over the heat sink, regardless of heat sink size.

Your statement that the air around a large heat sink doesn't get warm is untrue. It may *seem* not to be as warm because it is not as focused, but I assure you, the same amount of heat is displaced, just over a larger spatial area.

With adequate air flow, which the G5 most certainly has, regardless of whether the heat sink is large or small, the heat is transferred from the heat sink into the air and straight out of the computer. I don't know how I can say this any clearer than I already have...

JR

Message #61 - Posted 2007/04/22 - Jolly Roger

On 2007-04-21 22:30:10 -0500, The New Guy said:

Previously, Adrian wrote:

Jolly Roger wrote:

As I said else-thread, I have two 7200 RPM drives in my G5 and a constant temperature of around 27˚ Celsius is maintained.

I find a similar temperature in the drive bay. However, the SMART sensors within the drives which are reported by my Temperature Monitor Dashboard widget show 40 to 41 degrees Celsius ... which is still within normal operating temperature range.

And since the sensor is inside the drive, you have the side panel on, per normal operation?

I know my side panels are always on.

I'm sure he does as well, since taking the side panel off results in the computer upping the fan speed to maximum speed (eg in "wind tunnel mode") which is quite loud.

JR

Message #62 - Posted 2007/04/22 - Jolly Roger

On 2007-04-21 22:29:29 -0500, The New Guy said:

Previously, Jolly Roger wrote:

On 2007-04-21 20:30:04 -0500, The New Guy said:

I'm curious: when you put the side panel on, does it touch the section divisions? Or would air from the motherboard make its way up to the hard drive area?

Under normal circumstances, there's a hairline crack of space between the clear side panel and the dividers. So I don't see much air going that route when the front and back grills offer barely any resistance at all to the flow.

For my temperature tests, the wire of the sensor is about a millimeter thick, so the opening was also minimal, and I was actually about to put *both* side panels on during the tests.

When you took the temperature tests, was the side panel on, as per normal operation?

Both the translucent "air flow" side panel and the metal outer cover we closed during the tests.

JR

Message #63 - Posted 2007/04/22 - Daniel Packman

Previously, The New Guy <replytogroup@here.thanks> wrote:
....

Think of this....if you put an immense heat sink on a old video card, it may not even get warm. That's because the heat sink is up to the task. Now if the heat sink doesn't get warm, then air around it doesn't get warm. I don't understand why this concept is so difficult to grasp.

If the heat sink is huge, it can transfer heat to the
air of a larger area. This means that the heat coming
out the back might not seems as hot if a larger area of
air is moving at a relatively slow speed. But to keep a given cpu load at a given temperature, the heat content
of the air coming out the back is completely independent
of the size of the heat sink. You could have a cubic foot per second of air at 10 degrees over ambient or you could have 10 cubic feet per second of air at 1 degrees over ambient.

The worse the heat sink, the more air it needs flushed through it to cool it. And the hotter that air is going to be.

You might have a high volume of a air rushing across
a small heat sink, but the ultimate heat content of
this air will be the same, even if it is hotter.

Message #64 - Posted 2007/04/22 - G.T.

The New Guy wrote:

Previously, Adrian wrote:

The New Guy wrote:

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense. Regarding ram, you'll notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

Yes but it doesn't matter how big, small, efficient or inefficient the heat sink is ... there is still the same total amount of heat to be dissipated. A better heat sink simply spreads it around a larger area, reducing the hot spot on the component in the process. So good heat sinks are heplful in moving heat away from one spot and thereby protecting the component. However, the total amount of heat produced and the amount which has to come out of the back or top of the vented case will be the same.

This is pointless. I give up.

Thank you. You are absofuckinglutely clueless.

You people just don't understand heat sinks.

You just don't understand thermodynamics. Clearly.

Think of this....if you put an immense heat sink on a old video card, it may not even get warm.

Dude, it's just spread over more area. When the air that has been warmed up by that immense heat sink is squeezed out through the same size hole it's still the same temperature as the smaller heat sink. The only way to reduce heat generated inside the the computer is to reduce power consumption.

The immense heat sink does a better job keeping cool the part it is cooling but it does NOTHING to reduce the heat that that part is generating.

That's because the heat sink is
up to the task. Now if the heat sink doesn't get warm, then air around it doesn't get warm. I don't understand why this concept is so difficult to grasp.

The worse the heat sink, the more air it needs flushed through it to cool it. And the hotter that air is going to be.

You're fucking hilarious.

Greg

The ticketbastard Tax Tracker:
http://www.ticketmastersucks.org/tracker.html

Dethink to survive - Mclusky

Message #65 - Posted 2007/04/22 - Tim Streater

Previously, Jolly Roger wrote:

On 2007-04-21 22:27:13 -0500, The New Guy said:

Previously, Adrian wrote:

The New Guy wrote:

Well if we just take the CPU since that generates the most heat: with a well designed heat sink, it just won't get hot. Its all the function of the heat sink. If some of you would just read about heat sinks this would make a little more sense. Regarding ram, you'll notice that all high end ram now comes with heat sinks. So with a little bit of airflow the temps are fine. Its all in the heat sink design.

Yes but it doesn't matter how big, small, efficient or inefficient the heat sink is ... there is still the same total amount of heat to be dissipated. A better heat sink simply spreads it around a larger area, reducing the hot spot on the component in the process. So good heat sinks are heplful in moving heat away from one spot and thereby protecting the component. However, the total amount of heat produced and the amount which has to come out of the back or top of the vented case will be the same.

This is pointless. I give up. You people just don't understand heat sinks. Think of this....if you put an immense heat sink on a old video card, it may not even get warm. That's because the heat sink is up to the task. Now if the heat sink doesn't get warm, then air around it doesn't get warm. I don't understand why this concept is so difficult to grasp.

Yes, I'm getting tired of repeating myself as well. : )

As I've said numerous times before, the heat doesn't just go away magically because the heat sink is larger. Heat must go somewhere, and it goes into the air flowing over the heat sink, regardless of heat sink size.

Your statement that the air around a large heat sink doesn't get warm is untrue. It may *seem* not to be as warm because it is not as focused, but I assure you, the same amount of heat is displaced, just over a larger spatial area.

With adequate air flow, which the G5 most certainly has, regardless of whether the heat sink is large or small, the heat is transferred from the heat sink into the air and straight out of the computer. I don't know how I can say this any clearer than I already have...

The New Guy is sort of right that a larger heat sink runs cooler, but wrong about everything else. The aim of the game is to keep the temperature of the CPU (or whatever) below some level. If you have *no* heatsink, you might still be able to achieve that by having a vacuum cleaner (or jet engine, perhaps) blow air over it. Not really optimal. Or you could have a heatsink a few feet across and that wouldn't be optimal either. Why not? Because the name of the game is heat transfer.

As has been pointed out, the amount of heat to be gotten rid of does not change with heat sink size. You want a heatsink that is large enough to sink plenty of heat when the CPU suddenly has a lot of work to do. You want it small enough so that there will be some sort of temperature difference between it and the air flowing over it.

Remember that the heat generation cranks up as soon as the CPU load goes up. But there is a delay before the heat transfers to the air, the temperature sensor notices this[1], and the fans crank up speed.

In 'normal' use the heatsink may not be that warm. But in the extreme case it may well be - and that doesn't matter as long as the CPU temperature, which may nonetheless go up, remains within limits.

[1] unless the temperature sensor is on the CPU itself, but there will still be some amount of delay.

tim

Message #66 - Posted 2007/04/22 - Adrian

The New Guy wrote:

And the OS is on one hard drive so that hard drive is used far more than the other? Or are they hooked up in Raid 0 so they are used all the time equally?

One drive was 40c the other was 41c at the time of checking. No they are not operating as a RAID (it's an acronym by the way so I am using caps).

Adrian

Message #67 - Posted 2007/04/22 - Adrian

The New Guy wrote:

Previously, Adrian wrote:

Jolly Roger wrote:

As I said else-thread, I have two 7200 RPM drives in my G5 and a constant temperature of around 27Ë˚ Celsius is maintained.

I find a similar temperature in the drive bay. However, the SMART sensors within the drives which are reported by my Temperature Monitor Dashboard widget show 40 to 41 degrees Celsius ... which is still within normal operating temperature range.

And since the sensor is inside the drive, you have the side panel on, per normal operation?

Of course! (You're the one who is guessing and speculating about G5 tower performance ... I'm giving you facts ... these facts may not fit nicely with your expectations ... perhaps this is because much of what you are saying is wrong!)

Adrian

Message #68 - Posted 2007/04/22 - Adrian

Tim Streater wrote:

The New Guy is sort of right that a larger heat sink runs cooler,

... and nobody has disagreed with that

Adrian

Message #69 - Posted 2007/04/22 - Adrian

Jolly Roger wrote:

Both the translucent "air flow" side panel and the metal outer cover we closed during the tests.

He's clearly never opened up a G5 tower! The accuracy and fit of the panels is beyond anything I have ever seen in a computer case design. Of course in addition to a close fit outer panel there is an inner side panel of clear plastic which is designed to ensure good sealing and correct airflow. The intial idea that the G5 tower was a poorly thought out design in terms of cooling couldn't be further from the truth. Those hot G5 processors certainly provided Apple with some cooling challenges but it is patently obvious to anyone who has looked at a G5 tower that great care, effort, and expense went into managing the heat issue.

New Guy, just to really freak you out on potential cooling issues, you may not have heard that because of the large areas of open space inside the G5 tower there are companies producing bracketry to allow extra hard drives ... how many you ask ... up to 9 !!!

http://www.maxupgrades.com/istore/index.cfm?fuseaction=category.display& category_id=306

(watch for the line break in the URL)

I'm not going to argue over how good an idea this is but it does kind of show that things aren't anywhere near the limit in the standard configuration.

Adrian

Message #70 - Posted 2007/04/22 - Adrian

Eric Lindsay wrote:

The other problem Apple have is the one they make for themselves. If they solve all the cooling problems for a given size case, and the power consumption of the chips drop, they end up designing a smaller, neater case, and promptly run hot again. The iMac G5 after mine was a smaller case. They used the same case for the Intel design, and I am certain that ran at least 10C cooler. I very strongly suspect that soon after Santa Rosa chips appear, Apple will put them into an even smaller iMac case, and the temperature will go up again.

Yes, Apple are always pushing the limits of design. It amazes me how well the G5 processor appears to be heat-managed in the tight iMac enclosure. I would have thought that they would have at least required to use an aluminium back panel, perhaps with shallow fins to increase area to assist heat transfer ... yet they managed to keep things in spec within that small pastic panel! (Much of this thread has spread into G5 tower discussion where the case is enormous, with much more capacity for cooling. The iMac challenge was much greater IMHO)

Adrian

Message #71 - Posted 2007/04/22 - Ian Gregory

On 2007-04-21, G.T. wrote:

If you want to be taken seriously you need to take a course in thermodynamics. If you take one, you'll see the error of your ways. Heat doesn't magically disappear. A "properly designed heat sink" will have heat spread over a greater surface but if the method for removing that heat from the computer is to blow it out the case the air coming out of the case is still going to be the same temperature.

The other factor is the air flow rate. If you blow a huge volume of air over the heat sink then it will come out cooler. Basically if you look at the difference in temperature between the outgoing air and the incoming air, then that difference multiplied by the air flow rate will be a constant. So yes you can get the air cooler but only at the expense of having more or bigger fans. If the air is coming out cool then you have too many fans:-)

Ian

Message #72 - Posted 2007/04/24 - Adrian

The New Guy wrote:

Its like my Mini. I thought I might be
able to get better cooling without the plastic housing that holds the fan in place. I was able to mount the fan much closer to the heat sink. This seemed preferable in theory (my flawed theory that is!). But the fan was ramping up far more than with the plastic housing on.

<cough> Well, would you believe it ;)

Adrian

Message #73 - Posted 2007/04/24 - Michelle Steiner

Previously, Mike Rosenberg wrote:

Believe it or not, there _is_ already a George Foreman iGrill, and it does get its power from a computer, via USB. And I thought I was joking!

You may not have been joking, but they are.

<http://www.thinkgeek.com/stuff/looflirpa/igrill.shtml>

looflirpa backwards is ncevysbby (ROT 13 for those who don't want to know).

Support the troops: Bring them home ASAP.

Message #74 - Posted 2007/04/24 - Mike Rosenberg

Michelle Steiner wrote:

You may not have been joking, but they are.

<http://www.thinkgeek.com/stuff/looflirpa/igrill.shtml>

looflirpa backwards is ncevysbby (ROT 13 for those who don't want to know).

ROTFL!

<http://designsbymike.biz/macconsultshop.shtml> Mac-themed T-shirts <http://designsbymike.biz/musings.shtml> Mostly muckraking T-shirts <http://designsbymike.biz/prius.shtml> Prius shirts & bumper stickers <http://cafepress.com/comedancing> Ballroom dance-themed shirts & gift

Message #75 - Posted 2007/04/25 - Jolly Roger

On 2007-04-24 18:10:17 -0500, Michelle Steiner said:

looflirpa backwards is ncevysbby

fher fher jungrire : )

JR

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