Help diagnose the prob. with my comp

So here is the problem. I believe my comp is dead, but I want to figure out what happened. My comp. would just freeze out of no where sometimes. Then, when I restarted it, my monitor stayed black and at the top left corner, it keeps on flickering "Analog" then "Digital" and the power button on my monitor would turn on and off. Everytime I would restart the comp. it would do this. I couldn't even get to the windowns display screen or into BIOS. Another thing I might add is, when the comp was working, it would give me a message saying "Overclocking failed!" when I never even overclocked the comp?? Being frustrated, I brought the comp to my friend's place for further analysis. He was checking if the RAM was faulty, but nope, it wasn't. Then we used a diff. video card to see if my video card died, but it wasn't the prob. So he came to the conclusion that either my motherboard or cpu, or both are fried. What do you guys think? Could it be a PSU prob? Your help is needed.

Thanks.

Sounds like a dead PSU to me. The can be dead even though fans and stuff come on. I got a $10 PSU tester, best $10 I ever spent.