I turned my computer off one evening and when I pushed the power on button the next morning nothing happened! I tested the power at the Ups unit and I had 130 volts AC. I tested the cord and it was ok.
The next step was to test the push button and cable and they were ok. I checked the connection of the power supply cord to the Asus P5P800 mother board and it was tight. I suspected at this point that the power supply was defective so I bought a new Corsair 400 watt ATX power supply and installed it. The computer will still not power up when the button is pushed! At this point I double checked to make sure all of the connections were properly hooked up and they were as far as I could tell.
I assume that there must be a relay on the mother board that activates the power supply but I do not know its location so I cannot test it .
I need help to find out just how the power up is done thru the Mother Board, so I will know what to test next.
Thanks, Stevie G.

I need help to find out just how the power up is done thru the Mother Board, so I will know what to test next.
Thanks, Stevie G.

not sure if that even exist ,but it sounds like the board/ or cpu died.