Hi George you need to install the latest Hq anniversary patch from Race dept when installed this really helps also when up and working install crewchief its a must for big grids.
Before doing anything backup your whole master install so if something was to go wrong a few clicks of the mouse you can reinstall.
I have the same nvidea card it works just fine
Don't forget the hotfixes.
I would say if you are getting near 90 cars on grid using high settings with medium shadows you are doing pretty good