Older meanings...
Can you count the beeps or flashes?
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.
For the LCD...
If one of the Apple LCD displays detects an error condition, the power LED will flash in a certain pattern to indicate the issue.
Pattern |
Meaning |
short, short, short |
The display is detecting wrong video format or an unsupported resolution. Verify that your equipment is compatible and restart the computer. If the issue continues, reset the PRAM. |
short, long, short |
Make sure you are using the correct power adapter with the display. This alert will only appear on displays built in 2004 or later which require an external power adapter. |
short, short, long |
The display is detecting a backlight error. Check your display's power connections and restart the computer. If the problem continues, contact Apple or an Apple Authorized Service Provider. |