Not all that unusual for problems only to exhibit themselves under power rwequirements or cabling issues.
The following table lists the new tones and their meaning:
Tone(s) Description
1 tone, a 5-second pause, repeat No RAM installed
3 successive tones, a 5-second pause, 3 successive tones RAM does not pass data integrity check
1 long tone when holding down the power button Firmware upgrade in process. See About firmware updates for Intel-based Macs for more details.
3 long tones, 3 short tones, 3 long tones Firmware restoration from CD in process. See About the Firmware Restoration CD (Intel-based Macs) for more details.
http://support.apple.com/kb/HT2538
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.