Well honestly I'm not certain it is the video card. It could be any number of things I can think of so that's why I'm here!
Recently, with the Steam sale this week, I've found an odd issue that if I try to run a 3D game in any resolution under 1920x1200 it shuts my machine down.
It's a hard crash but it doesn't give me any usual "Windows did not shut down properly" errors. It just straight up shuts down and will boot up normally.
What'll happen is I'll play a game for a minute or two (rarely longer) and there'll be a bit of a stutter in the video then next thing I know my PC is completely off. Not in standby, no error messages or anything.
If I up the resolution to 1920x1200 the game will run for ever. The only things I could figure out was that since my native desktop resolution is 1920x1200 having two different resolutions was causing the problem; but when I lowered my desktop resolution to match an in-game res, it didn't help. It still shut my PC down like usual.
So far I've only noticed this with the new Steam games I've purchased and haven't tried it with anything else; but I'm not sure why Steam would matter in the equation here as the games engines have nothing to do with Steam.
I was thinking my video card could be shot, as I had problems about a month or two ago where my daughter pulled the power cord from my PC and when I restarted my system I was having some visual artifacts that you can get when a video card is dying. But after fiddling with some things it started working fine again and hasn't given me a problem since. And the card isn't giving any other signs of giving up the ghost as when it is running games it runs them perfectly well (as well as a 4850 can run many things at 1920x1200 anyway).
But it could be my mobo, and I guess
my processor but that seems unlikely, and it also seems somewhat unlikely that it's the mobo. All signs point to the video card for the most part but I've just never heard of an issue where you can only run one resolution or it shuts off your pc.
Oh, and my PSU is perfectly sufficent for my system so unless it's bad it's not that...and even if it were bad it wouldn't cause this unique of an issue.
Anyway, for reference, my pertinent system info:
Windows 7 x64 Home Premium
ASUS P5QL PRO 775 mobo
Sapphire Radeon 5850 512mb
Kingston HyperX 8gb (4x2GB) 1066 ram
Intel Core Duo E7400 2.8ghz
Antec Earthwatts E650 650w PSU
EDIT: All drivers are up to date as of yesterday too.