Completely uninstall all nvidia drivers, including motherboard etc from add/remove programs. Redownload them from nvidia.com with the latest being 91.31 for nforce. Also get this program: http://nvtweak.laptopvideo2go.com/
It will allow you to install collbits 1 or 3 as well as give you some other tweaks, you should be good to go after that. Also 91.31 has a bug that pops up a sli has been disabled message every time your computer starts up. A fix is on nvidia's website.
Hope this helps!