Overclocking The Asus N6600GT x 2
Before we completed our testing, we spent a little time overclocking our matched pair of Asus N6600GTs using the clock frequency slider available in NVIDIA's Forceware drivers after enabling the "Coolbits" tweak. Overclocking video cards in SLI mode is somewhat more difficult than overclocking a single card, however, because your peak overclock will be limited by whichever card overclocks the lowest. Each card is not overclocked individually...
In the end, we were able to wring out an additional 42MHz from the cores (8.4% increase), and an additional 90MHz from the memory (9% increase). While the cards were overclocked, we re-ran a couple of high-resolution tests with anti-aliasing and anisotropic filtering enabled using Doom 3 and Half Life 2. The higher clock speeds got us an extra 1.9 frames per second in Doom 3 (5.1% increase), and 2.34 FPS in Half Life 2 (5.7% increase).