Fill rate and memory bandwidth
Before we get to the game benchmarks, here's a quick overview of how the various cards we've tested compare in terms of fill rate (the ability to draw pixels and textured pixels on screen) and memory bandwidth. These numbers don't always determine in-game performance these days because shader arithmetic capacity has become at least as important as fill rate.

  Core
clock
(MHz)		Pixels/
clock		Peak
fill rate
(Mpixels/s)		Textures/
clock		 Peak
fill rate
(Mtexels/s)		Effective
memory
clock (MHz)		 Memory
bus width
(bits)		 Peak memory
bandwidth
(GB/s)
GeForce 7950 GT5501688002413200140025644.8
BFG GeForce 7950 GT OC5651690402413560143025645.8
Radeon X1900 XT62516100001610000145025646.4
GeForce 7900 GTX65016104002415600160025651.2
Radeon X1950 XTX65016104001610400200025664.0
GeForce 8800 GTS50020100002412000160032064.0
GeForce 8800 GTS 320MB XXX58020116002413920180032072.0
GeForce 8800 GTX57524138003218400180038486.4

The basic lesson here is that the GeForce 8800 GTS is a tremendously powerful graphics solution, especially in its higher-clocked "XXX edition" form. Although GTS 320MB cards start at $300, they compete more closely in terms of memory bandwidth with the Radeon X1950 XTX and GeForce 7900 GTX than they do with the incumbents in the $249-299 price range.

Note that the GeForce 8800 GTS 320MB results differ slightly from the GTS 640MB results. The 320MB card is a little slower in the single-textured fill rate test and a little faster at multitexturing. That's unexpected in a synthetic test like this one that isn't likely to run into a memory size constraint. We can probably place the blame for the difference at the feet of our BFG Tech GeForce 8800 GTS 640MB card, which shipped with a somewhat higher-than-stock 513MHz core clock and a lower-than-stock 792MHz memory clock.