I wonder if you guys don't have a high enough wattage power supply, enough amps, not 80-plus certified, runs REALLY hot, or if you have the video card attached to the same power rail as other devices.

It's possible that the video card isn't drawing enough juice.

Also you should remove some weird settings or go into the NVIDIA control panel and disable weird features to see if it runs better, and of course to update any drivers.

But remember not to mess around too much with your power supply it can kill you.