Before 2 years I bought video card 8600 GT, but every time when I start game in 3D mode the screen freeze and I hear delayed sound. 8600GT have a problem in 3D games, I don know what exactly is the problem of this NVIDIA Graphics Cards, but I know how to fix 8600GT freezing.
If you want to fix 8600GT random freezing in 3D games you need to decrease the values of "Core clock" and "Memory Clock" I decrease this values using the software RivaTuner, on Driver settings I choose "Customize" -> "System settings" - > "Performance"
There I chose values for "Core clock" under the default settings (I choose 396), for "Shader clock" I choose Link clocks 270MHz (871), for Memory clock I choose 350Mhz.
Now I can play all 3D games without freezing and problems.
I hope this helps you.