System Reboots but no BSOD or Error message

Is the video card overheating? Open the case and make sure that all the fans (including video fan) are clean and working properly. I'll try overclocking my Q6600 when I install my new motherboard next week

 

Sounds like a video card issue. It also sounds like you have Auto-Restart on, so make sure that's off (XP: right click My Comp>Properties>Advanced>Startup & Recovery Settings, uncheck Automatically Restart, Vista: Control Panel>System>Advanced>Startup & Recovery Settings).

If you did have Auto-Restart on, from now on you'll bluescreen when it happens and you can identify where the issue is.

 

I go with TMagic500. It has the symptoms of overheating... Could be simple in that you have too little or too much thermal paste. Though it is more typical of a video card problem, the 8800GT hasn't been a problem in our shops.
External pistol thermometers come in handy at a time like this.

 

Well I have changed my heat sinks on both of my cards and monitor the temps pretty close while playing, nothing over what they use to be. GPUs don't go over 50 and 55 Celsius so maybe it could be an individual RAM chip not getting proper cooling, but I've seen my card sold with only the GPU being cooled and not the RAM or Voltage regulators. I'll check my temps a little more, thanks for the swift reply.

 

I'd honestly take a look at the power supply as well, as even small brown outs can cause those kinda of issues. I had a similar situation that was fixed by replacing the power supply.

 

Good point. Sometimes we assume too much

 

Damn, I don't want to have to replace my power supply, that's expensive to replace. Maybe I'll try declocking for a while and seeing if it fixes my problem. On another note it did another random reboot after about 30 minutes of FEAR 2 but than I played for almost an hour without problems after.