Does it only do it on certain games or any game?
Do you have NVIDIA GeForce Experience installed? If you go into preferences you can optimize each game individually. This is also where you should update the drivers. 320.18 is the latest stable driver.
If you can access the Nvidia Control Panel, go to manage 3D settings, click on the global settings tab and click the restore button to restore all the settings to default. Then go to Configure SLI, surrond, physx and set the Physx settings processor to auto-select (recommended).
If it is still crashing in games, uninstall any software that EVGA included. I have 2x Asus 660's and I had random problems with the crap overclock software they included. I installed MSI Afterburner (also install Kombustor another stress test tool) since it can cap off the voltages. Make sure it is all default: power limit 100%, +0 clocks and auto fan speed.