What computer? Which operating system? How old is the computer? How many beeps? Which motherboard?
Tried reseating the motherboard, checking the power supply plugs, reseating RAM, replacing RAM, etc.
Tried replacing the power supply?
Tried putting a NEW CMOS battery?
Hope this helps and let us know more.
When power my Computer on it was a repeating beeping sound. Prior I took the Battery on the CPU out and put it back.