For some reason, after I installed the new NVIDIA drivers on CentOS 7, it stopped recognizing my monitor. Driver broken? A slight hack was required.
In /etc/X11/xorg.conf, look for these two lines :
HorizSync 28.0 - 33.0 VertRefresh 43.0 - 72.0
and replace them with
HorizSync 30.0 - 83.0 VertRefresh 56.0 - 75.0
Only by doing this, I was able to change the screen resolution in NVIDIA X Server Settings. For the exact values to put for HorizSync and VertRefresh, consult your monitor’s manual.