Recently at work I installed Ubuntu 10.04 on a workstation under my desk. After getting it installed I couldn’t get the monitor working at 1900×1200 as it was designed to do, so I hunted around on the intertubes for a while and found an option that got it running correctly without having to do lots of modeline weirdness.
In the video card section of /etc/X11/xorg.conf add the following line:
Option "ModeValidation" "NoMaxPClkCheck"
This disables pixel clock checks which probably only really matters for CRT displays (don’t quote me on that).