Looking through the overall scores of the cards you can see the GeForce 8600 GTS being slower than the GeForce 8800 family while the GeForce 8500 GT has a very poor result. Although there was only one instance, namely in 1920x1200 resolution of Battlefield 2142, when the GeForce 8800 GTS 320MB was considerably slower than the 640MB version of the same card, these two differ noticeably in 3DMark06 even in 1280x1024 with disabled FSAA. Note also that the GeForce 8800 Ultra scores over 11.000 points.
The mentioned advantage of the GeForce 8800 GTS over the GeForce 8800 GTS 320MB can be seen in the SM2.0 tests only due to the first test which is rich in high-resolution textures. The GeForce 8600 GTS falls farther behind the GeForce 8800 GTS in the SM3.0/HDR tests which are more computations-heavy than the SM2.0 group. The GeForce 8500 GT cannot score even 1000 points in either case.
Our supposition about the first test is true: the GeForce 8800 GTS outperforms the GeForce 8800 GTS 320MB more than in the second test. The rest of the results look normal and agree with the overall results for this group of tests.
The two SM3.0/HDR tests produce similar results except that the GeForce 8800 Ultra enjoys a bigger lead over the GeForce 8800 GTX in the second test while the advantage of the GeForce 8800 GTS over the GeForce 8800 GTS 320MB is, on the contrary, smaller. The results of the individual tests agree with the overall scores despite the use of full-screen antialiasing.