It's normal to see different options available for different cards using RivaTuner but loosing fan control on 178.xx series video drivers is NOT normal.
suggestions:
uninstall RivaTuner and the NVidia tweaker you have tried. (tell it you do NOT want to keep existing profiles)
Re-install the latest (probably the same as you are presently using) version of RivaTuner
Be sure to check in both the low level and the driver level tweak sections of the RivaTuner menus.
Good Luck.
(MSI, DFI, XFX, BFG, PNY, Ballistix) <-- never again to land in my PC :evil: