Overclocking The GeForce 2 GTS

Overclocking: The Memory

In order to determine which aspect of the GeForce 2 GTS is best to overclock, it is necessary to examine how the card reacts to overclocking the memory. The graphs of performance in Quake III Arena demo001 when the memory clock was increase in 5 MHz increments are shown below.

Note: Due to the extremely large amount of data that was collected in this section, it was necessary to place the graphs in a column graph orientation. The graphs do convey the same information as the above section, just in a different format.

This time it appears that the graphs look as expected them to, with noticeable differences between each 5 MHz increment. Once again we find that variation in values below the resolution of 1024x768x32 provides us with no useful information, however at this resolution and above we find the true key to overclocking the GeForce 2 GTS.

Without overclocking the GPU core at all, we were able to push the memory clock up to 408 MHz, 75 MHz above stock. At this highly overclocked speed, we find that the largest performance difference comes at 1600x1200x32 with a performance increase of 24.8%. No longer do our 5 MHz increments result in .1 FPS gains: we see gains as large as 13.6 FPS when at 1024x768x32.

What does this tell us about the GeForce 2 GTS. Well, it reveals that there is in fact a bottleneck in the system and this bottleneck is the memory bus. The 333 MHz memory clock speed that the GeForce 2 GTS defaults at does not provide enough bandwidth for the GPU to reach its effective fill rate. If this were not the case, and the memory bandwidth was more than adequate for the amount of information it needs to handle, we would have seen large increases in performance when overclocking the GPU and no performance increase when overclocking the memory clock. Since this is exactly opposite to the case at hand, the GeForce 2 GTS must be severely limited by the memory bus bandwidth. Even at the stock core speed of 200 MHz, the memory bus is being saturated by the GPU and as a result overclocking the memory resulted in large performance gains.

Now that we know what an important role the memory clock plays in the GeForce 2 GTS, we must can make a conclusion as to the best way to overclock the video card.