Shouldn't be bottlenecking actually... I have a phenom x4 mixed with a 670 and I have a bottleneck... To test it: Change your game settings/ resolution. If nothing changes your CPU is bottlenecking. Also check in task manager how much load is on the CPU + GPU. Use task manager and GPU-Z. If your CPU is at 98/99% load a lot of the time and the GPU is far under that, you are limiting your GPU.