Have you tried lowering the display settings in the game? If the same probelm happens consistantly through any settings, then you likely have a bad card. I experienced a similar situation with my GPU. I sent mine back with an RMA, but unfortunately all that was reported back to me was that the card failed a routine test, so I have no idea what was wrong with it.
No, I don't think that the CPU is the problem. Have you tried using MemTest86+ on your RAM? Does the freezing happen consistently, like in the same area of the game or when trying to load something in the game?