I turn on my computer and hear a series of beeps, or I see the power LED blinking a repeating pattern.

Every time you start your Mac, it performs some self-diagnostics. With these signals, the Mac is telling that it failed to pass those diagnostics.

1. Turn everything off, and disconnect all external USB and FireWire devices (except your mouse, keyboard and monitor if applicable). If you're using a third-party mouse or keyboard, disconnect those too. Disconnect your Ethernet cable if you use one. Disconnect scanners, external hard drives, printers, and so on. Now that your external stuff is disconnected, start the Mac and see if the external devices caused the problem. If so, reconnect them one at a time to see when the problem returns.
2. A series of beeps can indicate a hardware problem, usually bad or incompatible memory (RAM). On some computers, the power LED will flash as many times as the beeps, plus one, repeating the sequence every five seconds. The current beep codes for most other Macs are:

Beeps	Meaning
1 beep	no RAM installed
2 beeps	incompatible RAM installed
3 beeps	RAM failed test
4 beeps	problem with the boot ROM on the logic board
5 beeps	processor is bad

3. If you recently added RAM to the computer, you may want to try removing it (if you are comfortable doing this and have the right anti-static equipment).

If you still get the sad Mac tones, your problems are more serious—memory, the logic board, the hard drive, or an add-on such as a PCI card. At this point, if you still have trouble, you should probably bring the computer in for service.

Published March 24, 2009 12:00 PM
Last modified on November 25, 2011 11:01 AM