Random rebooting in games

[BitterAvatar]

Problem description:
My computer randomly resets itself while playing games. I've had it take a few hours, or sometimes only half an hour. There have been days at a time where it won't happen at all. This has specifically happened in Team Fortress 2 and Bioshock, yet I don't think I've ever had it happen in Supreme Commander. I get the feeling it might be driver conflict in Vista, but as of right now I am clueless.

I should also mention that I turned off 'automatic restart' for system failures to see if it was a BSOD, but it's still a hard reboot, and I'm not sure what exactly that means at this point.

Attempted fixes:
I've checked to make sure it wasn't overheating. At time of a crash my CPU was at 45 C and my GPU was at 75, which as far as I can tell from seeing other posts are somewhat reasonable temps.

I have also run Vista's memory diagnostic tool overnight and it found no errors.

Recent changes: Brand new system

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Operating system:
Windows Vista Home Premium x64

System specs:
Asus P5N32-E SLI
4GB (2GBx2) G.Skill DDR2 800
C2D E6750 (2.67 Ghz 1333 FSB)
EVGA 8800 GTX
PC Power & Cooling Silencer 750 Quad
DVD and DVD-RW: Lite-On SATA drives
Soundmax Integrated HD Audio
3 WD SATA 3.0 HDs; 160 gb, 500gb, 250gb

 

[engiNURD]

Can you loop 3DMark06 several times without it crashing?

Have you checked for updated drivers?

 

[Darth Bobo]

also; what are your MB temperature (Northbridge overheating?) and have you checked all internal connections?

 

[BitterAvatar]

I've looked at the connections, and everything looks good.
At the last crash the 'system' temp monitor was at 44 C. I'm not sure if there's another sensor that better records temps for the NB chip.

I have the most up to date video and audio drivers, my BIOS rev is recent, and Windows Update is current.

I am downloading 3DMark to give that a shot.

 

[engiNURD]

Did you get a chance to run it yet?

 

[brahim]

What kind of cooling do you have on your system ??? and do you oc ?

 

[BitterAvatar]

I've run it a few times but I can't seem to actually continuously loop it unless I bought the full version.

Everything is running stock. I have a Zalman heatsink on my CPU, a few powerful 120mm fans for good airflow, and stock cooling on my GPU.