I just got this (http://www.newegg.com/Product/Product.aspx?Item=N82E168...) PSU and now my computer is randomly shutting down. So far its only when gaming. I have a GTX 660 ti, i3 2120, 6 gb of ram. 630 watts is surely enough power. At first it was only skyrim, now its Rising Storm and Arma 3. So I know its not just the game itself. Please help.
I had the same issue some time ago. I deleted everything that came from nvidia, restarted my pc, downloaded the latest driver from the nvidia website without using geforce experience and that fixed it.