Using NVTweak, we enabled the panel for controlling clock frequencies in the ForceWare drivers. We started slowly, only raising the speed of the GPU and RAM in small increments and testing our results. When we reached a point where artifacts appeared or where the system became unstable, we backed off until we were sure that everything was operating normally. Our final overclock was 421MHz for the core and 557MHz (1.14GHz effective) for the RAM. The boost in RAM was modest, but the GPU overclock was an impressive 20%. To see how this affected our frame rates, we went back to Doom 3 and Aquamark 3 and re-ran them at 1600x1200 with 4xAA and 8x Aniso while overclocked.
As expected, we got immediate returns in both benchmarks. Over five frames per second were gained in Aquamark 3, also this still wasn't enough to catch up to the Asus AX800XL. A similar performance gain was seen in Doom 3, where the NX6800GT simply increased it's lead over the other cards. The differences between the frame rates before and after was close to, but not exactly, the 20% increase that we obtained when overclocking the GPU. During this period, we kept the card's fan set to the maximum speed, but noise levels were still kept within tolerable limits.