Long beep sound followed by flashing LEDs on boot

howesey said:

Just booted up my iMac, and every time I get a high beep from the speakers, followed by 3 or 4 flashes of the LED on the front, then the gong goes as normal and then OS X loads.

Anything to worry about?

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Apple said:

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.

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