It sounds like the video is tearing and pixelated. That usually happens when overclocking video cards too high. Did you try oc'ing the video? If so, back it down. I can usually get the gpu higher than the memory will go, so try that. Did you try lowering the setting for video in the game? Get back to me on those things and Ill talk to someone who knows more about games. (I dont play em much on my Macs).