8600 GTS freezing and crashing.

I'm running a nvidia 8600 GTS when I play games such as sins of a solar empire or starwars battlefront within 20 minits of starting the games the screen freezes pixilates red and then crashes, sometimes showing the blue screen of death. I then have to manualy restart the system.

I can rule out a couple of things:

Firstly updating and rolling back drivers seems to make no difference.
Secondly It's not overheating as I just installed a new fan into my PC.

Any ideas?

Have you checked the temps at load just to confirm that its not overheating?

Yes its not to do with the fans, my current theory is that it might be something to do with the dual core processor I'm running.

It could be a problem with your operating system, or configuration.

How long ago did you put the Fan in?