File: /etc/X11/xorg.conf

Section "Screen"
       Identifier      "Default Screen"
       Device          "geforce256"
       Monitor         "S/M 950p"
       DefaultDepth    24
       SubSection "Display"
               Depth           16
               Modes           "1024x768" "1600x1200" "1280x1024" "800x600" "64$
       EndSubSection
       SubSection "Display"
               Depth           24
               Modes           "1024x768" "1600x1200" "1280x1024" "800x600" "64$
       EndSubSection

EndSection