Computer lockups

[Astray]

For the past few months I?ve been having problems with my computer freezing while playing 3D games or other video intensive applications. I?ve ruled out it being a software issue, I?ve had the same problem on Linux, Windows Vista, and Windows XP. I?ve tried various drivers for my video card, and it happens regardless of which one it is. I?m not over-clocking anything, and never have. My BIOS is using all the default settings. I?ve ran Prime95 for 2 days without any lockups, and memtest86 doesn?t show any errors.

Here?s my current hardware:

CPU: Intel Core2 Duo e4300
Motherboard: MSI P965 Platinum
RAM: 2 GB DDR2-SDRAM
Video Card: nVidia 7600 GS
HDD: 74GB Raptor, 250GB SATA2
PSU: OCZ ModStream 520w

It also seems to do it fairly randomly, at times, I can play for three hours and have it never happen, and at other times it can happen the moment the game loads. There?s no bluescreens or anything, and nothing shows up in the event viewer.

 

[Noema]

Bad PSU perhaps not providing enough juice to the GPU when it needs it (games)? That would explain why Prime95 and Memtest86 run fine since they don't stress the video card at all.

Or perhaps the Video Card is dying.

 

[Job]

how does it lockup? Does the sound stutter? Does it reboot? Or does it just sit there?

 

[Roguestar]

Go to nvidia.com and get their diagnostic tool called (IIRC) nTune, and find out what kind of temperatures it gets up to by running 3Dmark2006. Could be the fan stopped or is clogged on the graphics card.