from hothardware:
It is little difficult to summarize the new GeForce 8800 GTS 512MB card’s performance. In games or benchmarks where fillrate and shader performance are the limiting factors, these new cards are excellent performers and can outpace even a GeForce 8800 GTX. But in situations where memory bandwidth and frame buffer size are more important, like say at high resolutions with anti-aliasing and anisotropic filtering enabled, the GeForce 8800 GTS 512MB can’t quite keep up with the more expensive GTX due to its narrower memory bus and smaller frame buffer. Generally speaking though, the GeForce 8800 GTS 512MB’s performance is better than the original 640MB GTS and the relatively new 8800 GT and on-par with the GeForce 8800 GTX at lower resolutions. Crank up the resolutions, however, and the GTX (or Ultra) is still the king of the hill.