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Archived - Power On Self-Test Beep Definition - Part 2

Products introduced after October, 1999 use a revised set of power on self-test beeps during startup. This article describes each one.

Refer to Power On Self-Test Beep Definition - Part 1 for information on earlier computers.

This article has been archived and is no longer updated by Apple.

The power on self-test resides in the ROM of the computer. This test runs whenever the computer is turned on after being fully shut down (the power-on self-test does not run if the computer is only restarted).

If a fault is detected during the test, you will not hear a normal startup chime. Instead, the system will beep as explained below. If you experience one of these beeps, you may call your Apple Authorized Service Provider for additional troubleshooting assistance.

1 beep = no RAM installed
2 beeps = incompatible RAM types
3 beeps = no good banks
4 beeps = no good boot images in the boot ROM (and/or bad sys config block)
5 beeps = processor is not usable

In addition to the beeps, on some computers the power LED will flash a corresponding number of times plus one. The LED will repeat the sequence after approximately a 5-second pause. The tones are only played once.

Note: In this case, a flash is considered to be 1/4 second or 250 ms or greater in length.

Last Modified: Jan 10, 2012
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  • Last Modified: Jan 10, 2012
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