I find this problem odd because the 8800GT works great with RivaTuner but for some reason now that my GTS (512) is installed I cant get into any fan or overclocking controls.
 
I'm using V2.06 which I believe is the newest one. I thought it might be a driver issue so I even got driver cleaner pro, but still having the same problems.  
 
I reinstalled RivaTuner and it says that my disply drivers are not supported. Should I go to a previous driver?

There is a fix for this. Lemme search the RivaTuner site and get back to you shortly.

OK found it. Read the whole thread. there is more detail as you go.
 
http://forums.guru3d.com/showthread.php?t=246531

I really appreciate the help! Fixed it right up.

yer welcome!