I've recently bought a Gainward Phantom GTX 670 to replace the Apple branded HD 5870 in my Mac Pro 3.33 hex. Overall, it's a significant upgrade, as shown by the attached Heaven results. It's also quieter than the 5870, both at idle and under load. The card's twin fans exhaust through the top surface of the housing and so I have removed the upper 2 PCI blanking plates, allowing the airflow from the PCI fan carry the warm air out the back of the machine. This strategy seems to work and everything seems to be running well with one exception. Unfortunately it's a show-stopper as far as I'm concerned and that's Civ 5: Gods and Kings. When I try to start or load a game, windowed or fullscreen, the game almost always quits unexpectedly before the map loads. Even on the rare occasion that the map does load, there are graphical glitches, for example I have seen the hex grid appear as thick white lines. Has anyone else had problems running Civ with PC NVidia cards? I'm hoping that updated drivers will be released soon and that this issue will be resolved. In the meantime, it's back to the 5870 for now.