It started last week when my computer was restarted and wouldn't POST. Since then, I've gone through all that I can to get it to boot. I've replaced the power supply, motherboard, and CPU. I've tried without the harddrives, I've tried with nothing but the video card plugged in. I've tried various combinations of the old power supply/motherboard and the new.
I'm about to pull out my hair here. Any clues as to what is wrong would be very appreciated.