I hope these still hold effective...
One long beep followed by two short - Graphics cards faulty or inserted incorrectly.
Two long beeps and three short ones - Possible flat battery.
One long, one short then four short beeps - BIOS checksum error (possible new motherboard).
Three long, two short then four short - Keyboard control failure (maybe damaged cable).
No beeps at all - If fan and lights are on the cpu has blown