Computer Randomly Shut Down

[k0rana]

I'm trying to help my friend out with his computer. It's a relatively new computer (about a month ago), and it was built by some other friend.

Here are his specs (off the top of my head, I don't remember the specifics or his actual hardware)
Windows Vista x64
3.0 Ghz Phenom II X4 940, with Arctic Cooler Freezer (I think it was overclocked to something higher.)
2 x 2GB DDR2 memory
SATA HDD
Rosewill 650W PSU
1 GB nvidia video card
gigabyte motherboard
dvd-burner

He called me on his cell and told me when he was playing a PC game (Left 4 Dead), the computer randomly shut down on him. He couldn't turn it back on. As in no power LED, no fans spinning, nothing popped up on the screen, didn't make a sound...nothing!

Then I told him to turn off the PSU, turn the PSU back on, and then turn the computer on. It worked somehow.

The thing is I want to know why it randomly shut down on him so that it doesn't happen to him again.

A faulty power supply? Bad motherboard? Bad video card? High temps? Didn't overclock it correctly?

If it's the PSU, anyone know if there's a program that tests for faulty PSU's?

 

[Tenenbaum]

There is no program to test for faulty PSU's.

I'm suspect it is high temperatures as the computer will shut it self down to discontinue the overheating.
Tell him to download HWMonitor, or RealTemp, and give us the temperatures of everything, and let me know.


And also, has this happened more then once?

 

[k0rana]

This is his first time that it happened to him on his new computer. Tomorrow I'm going to his house to check it out, and will keep you posted when I do.

Edit:
I didn't go to his house. My friend said he's fine in his current situation and doesn't want any help.