Computer simply powers off sometimes - How to diagnose?

[Shaitan00]

I have an old P4 computer that I've been using constantly for about 5 years, about a month ago the Power Supply (500W) started making a high-pitch sound - so a few weeks ago I went to a local store - bought a new one (525W) and put it in ...

Everything worked fine at first (simply browsing the net, etc... basic stuff) until 4 days later we tried to play Unreal Tournement and within the first 30seconds in-game the computer simply powered off - this was reproducible on-demand... This also started occuring sometimes when watching shows (either AVI or streamed on the web)...

The only way to get the computer to power on again is to flip the switch in the back (on the Power Supply), wait 30-45 seconds, switch it back, and then power on the PC... Then everything works fine until the next time.

Obvisouly my first reaction was "defective power supply", so I returned it and replaced it with another one (same model) - first thing I did was test playing Unreal Tournement and movies and it worked fine for the first 3-4 days ... now yesturday while streaming sosme TV shows it happened again ...


That's pretty much the entire story ... my question ... how do I troubleshoot the issue?
- Is this a video card issue (only occurs when playing games or watching movies)?
- Is it a power supply issue (too strong? not compatible? sucks because no more return)
... RAM ... Mobo ...? did I just get unlucky?

Is there something I can install, some kind of monitoring software? Something that can help indicate where the issue lies ... Given that this is intermittent I can't just start removing hardware piece-by-piece...

Any advice would be much appreciated...
Thanks,

[tommyshango]

By any chance is it dirty and dusty on the inside? Often overheating is a huge issue and very hard to pin point.

Aside from that there isnt a straight answer. The only true way to pinpoint the problem is to take a known working component and replace a questionable component and just keep going down the line. Once it works then hopefully the bad one was the one you replaced. You can of course do it quicker by taking out a component and putting it in a system that works stable. For instance take out the memory and put it in a working system if that system crashes then you have bad memory. You can run seperate tests as well such as memtest. But overall thats how you troubleshoot.