NVIDIA and ATi offer several quality modes in their drivers which have more or less pronounced effects on performance and image quality. These modes use very different approaches for optimizing performance, making a direct comparison difficult. What we are interested in here is the performance at the highest available quality level. Again, you'll find the scores of the other modes as well, in gray.
The scores of the NV30 (FX 5800 Ultra) and NV35 (FX 5900 Ultra) are practically identical. The NV35's lower chip speed seems to be offset by the better memory subsystem. After all, the pixel pipelines need a steady supply of data.