Here's how I do it. su to the root user, and edit /etc/X11/XF86Config-4. Locate the following section (it may differ for your current setup): Section "Screen" Identifier "Default Screen" Device "Generic Video Card" Monitor "Generic Monitor" DefaultDepth 24
[...]
SubSection "Display"
Depth 24
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
EndSection
I should probably add that after saving, you'll need to log out and
restart X by pressing Ctrl+Alt+Backspace.
Clint