I'm sorry, you are gaming without any drivers for your graphics card? I'd be surprised if it didn't crash, then. Do you mean you left the ones installed by windows or windows update?
The sure way to test the card would be to install it in another computer. If that is not possible, Furmark is a good tool to stress your GPU and see if it is the cause. Anyway, if you can't even get the drivers to install after a clean OS installation, then it is pretty clear that the card is faulty.