OK, i have got my old 8500GT back and installed it. vista recognized right away and let me use it as a dedicated physx card. i set it through the nvidia control panel for physx. and i figured i would let y'all know how it went.
i did a 1min benchmark through fraps, showing the average frame rate, on the physx fluids demo, from the nvidia website. and i ran it on the CPU, 9800GTX and 8500GT. nothing was changed from test to test. 9800GTX being primary display. cpu overclocked to 3.6GHZ with ram running at 1600MHZ. the video cards were at stock clocks.
this is with the physx fluid demo. it's the "tube" one with the water going through the tube. this consisted of me doing the test with one water emitter on and another with 7 of them on.
light load (one emitter)
with a heavy load (7 emitters)
so the results speak for themselves. the more stream processors the card has, the better the frame rate.
but now on to UT3 with the Physx mod pack, also from nvidia website. this was also 1 min of playing through the game with 15 (max) bots on the heatray physx map. hardware physx enabled. the settings are, details maxed out at 1680x1050 with no AA and 16x AF.
with 8500GT for physx: 34FPS
with 9800GTX for physx: 28FPS.
so not a huge improvement there, but with hardware physx turned off and cpu doing the physx the game was totally unplayable. I'm talking like 1-3fps.
so there you have it. 8500GT in physx is not too bad. but i would recommend something with a little more horse power, like a 8600GT or 9500GT.
if any body else knows of any physx, tell me and i will run them