I have had my system for over a year now with no problems. I bought a new GPU and power supply because of black friday deals and with new games (GTA5, ACU) coming out. I bought a ASUS GeForce GTX 780 Ti and a Corsair CX750M from newegg. I upgraded from a 660 and a CX500. It installed fine and all was well until I turned Assassin's Creed on max graphics, when some fans (I'm guessing the GPU fans) spun up very quickly and then my PC restarts. There was no BSOD or anything like that. I decided to test it on high settings on ACU and there were no restarts. I then tried BF4 on ultra, and it was fine on small maps with not much happening, but when it goes to a large map or when it seems to have to push, the fans spin very fast and loud and then the PC restarts. I turned it down to high on BF4 (with my old GPU, I could play on ultra with around 30fps if I remember correctly with no restarts or crashes) and I played on a small map for a game, and the monitoring software that came with the GPU said I reached a max GPU temp of 76 C. Is it a faulty GPU? Or do you have another idea of what could be causing it?