How much sleep load per MB of RAM?

In <42b75fd8@news-1.oit.umass.edu>
Subject: Re: "ramBunctious" SEEMS like a good idea - - - Opinions? On 2005-06-21 Joe Heimann wrote:

I suspect Apple did not do so because RAM that meets their specs for power usage in sleep mode does not consume all that much power. From the developer notes for the 15" PB, they specify that RAM should not use more than 6 mA/128 MB from the 2.5 V power supply. At a max RAM of 2 GB, that translates to about a .25 W, not a very large draw. Those are typical figures in the specifications for other Apple notebooks as well.

16 * 6 *2.5 = 16 * 15 = 240 mV

So, at 512MB, my IBook G4 should soak up . . .

First, my battery is about 4 times the Voltage (11V - 12V) roughly. So presumably it should take no more than 1.5 mA / 128 MB, right?

My old G3 with 640 MB took about 15 mA in sleep.
Hm. That's about *twice* that.

Let's check the new G4:

In 3.5 hours it went down by 60 mAh. 17mA.

So, I'd like to buy a further 1GB.
Does that mean my sleep drain will then be three times as much? 51mA? That means 24h sleep will burn up 28% of my brand new battery.

Here's another question:

If I buy cheap RAM, might it consume more power in stand-by mode?

I'm thinking of buying this:

http://www.kingmax.com/news/news_product/news_p20041130.htm

It costs about 1/4 of Apple's RAM.

-- Peter ( renzlandATgmailDOTcom )

lineeaterlineatereatupthisline

In <430e9399@news-1.oit.umass.edu>

Thanks Joe. One more question -- how do I go about checking to see that it meets those other specs? I found this very detailed spec sheet for the above memory: http://www.kingmax.com/support/Kingmax_DDR_SO-DIMM.pdf

On page 11 it says:

Pre charge power down standby current: 80 mA (for the 1GB)

That looks like what I'm looking for.
That would mean (modulo losses and other loads)
an additional 20mA (+ the 17mA with native RAM).
That's consistent with your estimate of "double".

So, looks like I'll go and get it. :-)

(The G4 already has 3 swap files doing almost nothing.)

-- Peter