Desktop Macintosh: Hold power button to reset

On some models of iMac and Mac mini, the computer's power button replaces the power reset button and programmer's switch.

The following computers do not have a power reset button or a programmer's switch (NMI button, also known as a NMI or nonmaskable interrupt button). You use the power button for these functions.

  • iMac (Flat Panel) - all models
  • iMac G5 - all models
  • eMac - all models
  • Mac mini - non-Intel-based models
  • Power Mac G5 - all models
  • All later iMac and Mac mini computers
This article has been archived and is no longer updated by Apple.


Press the power button for one second to put the computer to sleep. To wake the computer from sleep, press the power button for less than one second or press any key on the keyboard.

Shut down

To shut down the computer, select Shut Down from the Apple menu (or from the Special menu if you are using Mac OS 9). You will be prompted to save any unsaved documents.

If the computer is unresponsive, you can force the computer to shut down by pressing the power button and holding it for at least 5 seconds.
Important: If you do this, information in any unsaved documents may be lost.

Firmware updates

From time to time, Apple has provided firmware updates to address certain issues that cannot be addressed in updates to software. On earlier computers, the programmer's switch was used to install a firmware update.

Follow these steps in the event that a firmware update is needed for these computers with no programmer's switch:

  1. After downloading and running the firmware update, shut down the computer.
  2. Wait until the computer is shut down and the power light is off.
  3. Press and hold the power button for several seconds.
  4. The computer will signal that a firmware update is ready to be installed by making a steady tone and the power button light will quickly flash several times for several seconds.
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