The refresh rate reported by 3 different apps is different (screenshot attached) - nVidia driver 169.12:
nVidia settings (Gnome and KDE) - 75Hz (applied and saved to xorg.conf)
KDE Control Center - 50Hz
Gnome Screen Resolution - 51Hz
It is of concern to me because when I tried to change refresh rate from 1280x1024 to 800x600, I got an "Input Signal Out of Range". I noticed it was also trying to select a refresh rate in the 50s. When I changed (using the KDE Control Center) to 800x600 using 82Hz it changed without issue.
The thing though is that I know from past experience that 60Hz or 75Hz are the two refresh rates that work without issue across resolutions. How can I have it that everything detects 75Hz (or 60Hz)?