Which operating system are you running?
There is an archive at NVIDIA of old and beta drivers but you need to input the OS to get to the relevent drivers
I find RivaTuner too "clunky" for something as simple as fan speed control, the Asus Smart Doctor is fairly lightweight in comparision. Obviously it is for Asus cards only though.
I have emailed Asus Tech Support for a solution but the clowns wanted me to install a 175.xx driver, they didn't read my email properly that the issue was with the 180.48 driver.
I really don't hold out much hope of a fix anytime soon so I guess if I want to have fan control with the new driver I might have to return to RivaTuner.