Ok, I just got my GTX 660FTW SIG2 video card back from the RMA and it was working normally for a couple hours and then started to artifact and crash repeatedly. It stopped finishing tests in 3DMark and Tomb Raider and Minecraft started crashing. So, I talked to an associate who said it may or may not be the GPU. Do you all have any suggestions on what the problem may be? The Power Supply is checking out and I have run MemTest and it checked out. (specs in signature)