so the last couple of days i got a freeze, restart, and computer bios says the cpu fan speed is too low. i was planning on replacing the cpu/heatsink so i swapped them with a new opteron and now have the same problem still. i crack open the case to watch the fans and the regular heatsink fan is spinning happily and i notice a fan that's onboard the mobo is pulsing (5400 rpm to 2000rpm to 5400 to 2000 blah blah) it's doing it at a fairly mechanic/consistant rate and i'm not sure what the fan is even called so i can buy a new one, or if it might be my motherboard, or it might be my psu ? anyone have any answers, feel free to chime in, i can't find a manual / diagram online and dont have the paper docs anymore (stored back at home). the fan in question is the gray square in the lower left quadrant that has a black inner circle with asus on it.