Adding a resolution & refresh rate using NVidia driver?

[Sasha Tsykin]

If your monitor's settings were not detected automatically, that means
you have to manually change them in your /etc/X11/xorg.conf file. Here's
how.

$ sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf_backup
$ sudo gedit /etc/X11/xorg.conf

Search for the "Monitor" section

Type in the name of your monitor (in the Identifier field), and the
VertRefresh and HorizSync specifications in the required feilds. If you
don't know these specifications, look them up on the net for your
monitor. Then, in the various "Modes" sections, add your chosen resolution.