Computer turns off by itself when playing 3d games

[TonyH]

My computer specs are:

Windows XP SP2
MSI K8T Neo m/b
AMD 64 bit 3400+ cpu
Powercolor x800 XT Platinum video card
Sound Blaster Live!
Western Digital 120 GB IDE HDD (Master, WIN XP installed on it)
Western Digital 40 GB IDE HDD (Slave)
Western Digital 200 GB SATA HDD
Lite-on CD burner (LTR-52246S) - Master
Pioneer DVD-RW (DVR-107D) - Slave
1 GB of ram (Kingston)
Thermaltake 420W Power Supply



Everything was fine till about a week ago. Lately when trying to run a 3d game such as Quake 3 or Guild wars, you can play for 5 min or even 2 hours and then the comp will just turn off without warning. It then won't restart immediately. Often you have to wait 5 to 10 min before you can re-start it.

Possible causes:

(1) Power supply is underpowered. I wouldn't have thought so, everything was fine with this configuration for about a year till now.

(2) Power supply is faulty or damaged. Its possible. I had a couple of power surges a few weeks ago. My comp wouldn't turn on again for about half a hour.
I've installed a surge protector since but may have been too late.

(3) Video card is faulty. A few weeks ago I installed one of those ATI Silencer heat sink and fans. My original fan was rattling and decided to change it. Maybe I damaged some component on the Vid card when I switched heat sinks? I was trying to be careful but maybe I stuffed something.

I can't think of any other reasons. Nothing is overclocked on my system.

Any thoughts?

 

[BASSMASTER]

That's a lot to run off a 420W power supply IMO, I would try upgrading that. Even if that's not the cause of the problem, it's probably a worthwhile upgrade looking at your system specs.

The only other thing I could think of is the cpu temps, have you checked them in your BIOS yet?

 

[nuke]

its pretty good computer.... he doesn't even need to upgrade. 420w psu is good enough also. I would go and check the temp in bios, or check if it has any spyware, or virus on your computer also.