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Resetting the SMC

Message #1 - Posted 2008/07/04 - Michelle Steiner

I came across this article today. It addresses some problems that have been reported here periodically.

<http://support.apple.com/kb/HT1543>

Summary
The System Management Controller (SMC) is a chip on the logic board that controls all power functions for your computer. If your computer is experiencing any power issue, resetting the SMC may resolve it. The SMC controls several functions, including:

* Telling the computer when to turn on, turn off, sleep, wake, idle, and so forth.
* Handling system resets from various commands.
* Controlling the fans.

Products Affected
Mac mini (Early 2006), Mac mini (Late 2006), Mac mini (Mid 2007), iMac (24-inch, Late 2006), iMac (Early 2006 17-inch), iMac (Early 2006 20-inch), iMac (Mid 2006 17-inch), iMac (24-inch Mid 2007), iMac (20-inch, Mid 2007), iMac (17-inch, Late 2006), iMac (17-inch, Late 2006 CD), iMac (20-inch Late 2006)

Note that resetting the SMC does not reset the PRAM. Resetting the SMC will not resolve issues in which your computer is unresponsiveãin these situations, restarting your computer will generally suffice. If your computer isn't responding, perform these steps one at a time, in this order, until the issue has been resolved:

1. Force Quit (Option-Command-Escape).
2. Restart (Control-Command-Power).
3. Force Shut Down (press the power button for 10 seconds).

Resetting the SMC can resolve some computer issues such as not starting up, not displaying video, sleep issues, fan noise issues, and so forth. If your computer still exhibits these types of issues after you've restarted the computer, try resetting the SMC. To reset the SMC on an iMac (Early 2006), iMac (Mid 2006), iMac (Late 2006), or Mac mini (Early 2006):

1. From the Apple menu, choose Shut Down (or if the computer is not responding, hold the power button until it turns off).
2. Unplug all cables from the computer, including the power cord and any display cables.
3. Wait at least 15 seconds.
4. Plug the power cord back in, making sure the power button is not being pressed at the time. Then reconnect your keyboard and mouse to the computer.
5. Press the power button on the back to start up your computer.

The iMac (Early 2006) and later models do not have a button on the main logic board for resetting the SMC, which eliminates the need to remove the computer's cover to reset it (as required for some earlier models).

Support the troops: Bring them home ASAP.

Message #2 - Posted 2008/07/04 - Claude V. Lucas

Previously, Michelle Steiner wrote:

I came across this article today. It addresses some problems that have been reported here periodically.

<http://support.apple.com/kb/HT1543>

Summary
The System Management Controller (SMC) is a chip on the logic board that controls all power functions for your computer. If your computer is experiencing any power issue, resetting the SMC may resolve it. The SMC controls several functions, including:

* Telling the computer when to turn on, turn off, sleep, wake, idle, and so forth.
* Handling system resets from various commands.
* Controlling the fans.

Products Affected
Mac mini (Early 2006), Mac mini (Late 2006), Mac mini (Mid 2007), iMac (24-inch, Late 2006), iMac (Early 2006 17-inch), iMac (Early 2006 20-inch), iMac (Mid 2006 17-inch), iMac (24-inch Mid 2007), iMac (20-inch, Mid 2007), iMac (17-inch, Late 2006), iMac (17-inch, Late 2006 CD), iMac (20-inch Late 2006)

Note that resetting the SMC does not reset the PRAM. Resetting the SMC will not resolve issues in which your computer is unresponsiveãin these situations, restarting your computer will generally suffice. If your computer isn't responding, perform these steps one at a time, in this order, until the issue has been resolved:

1. Force Quit (Option-Command-Escape).
2. Restart (Control-Command-Power).
3. Force Shut Down (press the power button for 10 seconds).

Resetting the SMC can resolve some computer issues such as not starting up, not displaying video, sleep issues, fan noise issues, and so forth. If your computer still exhibits these types of issues after you've restarted the computer, try resetting the SMC. To reset the SMC on an iMac (Early 2006), iMac (Mid 2006), iMac (Late 2006), or Mac mini (Early 2006):

1. From the Apple menu, choose Shut Down (or if the computer is not responding, hold the power button until it turns off).
2. Unplug all cables from the computer, including the power cord and any display cables.
3. Wait at least 15 seconds.
4. Plug the power cord back in, making sure the power button is not being pressed at the time. Then reconnect your keyboard and mouse to the computer.
5. Press the power button on the back to start up your computer.

The iMac (Early 2006) and later models do not have a button on the main logic board for resetting the SMC, which eliminates the need to remove the computer's cover to reset it (as required for some earlier models).

I've needed to do this a couple of times on my 20"iMac since I got it last Nov because the fans went berserk...

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