So... Here goes.

A friend has a computer which recently began shutting off without warning. It just goes click and the whole thing turns off. No shutting down stage, no BSOD - nothing. It then takes 2 minutes or so before it will even respond to you pressing the power button to turn back on.

It will crash in any situation - in normal windows (XP pro I think), in windows safe mode, and even in the bios menu when we were looking in there.

At first he said it was only working in the evenings - it was on strike and refused to put in normal working hours, but now it will shut down anytime. This led me to believe that we're dealing with something overheating, so we cleaned out all the heatsinks etc. But it still crashes. So the newest theory is the heatsink needs reattaching to the CPU. However, when the computer has stayed on long enough, he checked the temperatures and they all were fine, and this was more than one occasion. And then it turned off.

So what I'm asking is:

1. What do you people out there on this interweb thingy think is wrong?
2. How do we fix it?

Please note longer diagnostics are practically impossible because there is no reason to think the computer will stay on more than 3 minutes.

Feel free to ask anything you feel you need to know.

Thanks!

I would suspect the power supply is bad. Is the fan on the power supply turning on?

I honestly don't know... I didn't have too much time to look at it and unfortunately most of that was while it wasn't on... I'm going to see the owner tonight so I'll pass on the idea to check.

Thanks

If it's dirty inside, it can also be overheating
interior cleaning tutorial

As you've stated, it's awful hard to diagnose anything if it won't stay on long enough to do anything.

I also suspect the PSU - but would confirm it by trying the appropriate steps in this system stripdown guide: http://www.bleepingcomputer.com/forums/topic70216.html

You'll probably have to start out around step 5. If it still reboots after 3 minutes with all the stuff removed - then it's one of the remaining components that's causing the problem. Then it's just a matter of substituting known good parts for the one's that are still in the case until you figure out what causing the problem.

I've passed on the message about it probably being the PSU, and I'll try to keep you updated. I'm a bit hesitant to take the whole thing apart since it crashed out in Bios. Wouldn't that mean that the problem is not in the components but either the mobo or PSU? Or can hardware problems work their way into bios? All I'm certain of is that computers hate people.

Thanks

Thanks for the replies... Turns out it was the PSU, although the fan was working.

Glad you got it Solved. Thanks for posting your solution!!