I have a computer that is giving me fits. The problem is the hard drive will click and turn off and then it sounds like they restart and eventually the computer will lock up. This happens to 2 different drives (Western Digital 80 GB IDE's) that I have tried. I have run the WD Diagonistic programs and it found no problems on either drive. My question is does this sound like a hard drive problem or could it be the motherboard or RAM going bad.
Try a different power supply. If its done the same thing to two different hard drives and neither one reported problems, id say its not the drives. memory wouldnt cause it. Motherboard maybe or bad cable. If the system works fine otherwise I would bet the power supply is cutting off the 5v lines for a second and then turning them back on.