Hello Georges,
According to the TPS, the beep code indicates power control fault.
That powersupply fits the requirements: minimum 550W, minimum 3amps 5V stand by current.
Have you confirmed that the power supply is working properly?
You said you "inherited" this board, I guess it was maybe on the junk pile for a reason?
Jason
EDIT: I powered on my reference Hanlan Creek system, after disconnecting the auxilery power signal header and it booted without issuing an error code.
