On some boards, it's a matter of connecting two pins on a jumper on the motherboard, the case switch performs that connection. That should translate to (if these two pins are connected, the power supply is supposed to be on, until the drop and then go on again.)
Your BIOS manual might tell the tale, some careful experimentation might as well. Insert standard caveats here. Remember 120V at 15 amps = Crispy Geek. -- Hacksaw = David Charles Todd BBN Technologies = Hacksaw's Employer Hacksaw's Opinions != BBN Technologies' Opinions Linux understands you.