Originally Posted by Jan Simonson
My Fedora 8 system is running on an AMD Athlon 2200+ with a Samsung SyncMaster 244T connected to a GeForce 5200 via a DVI cable. The monitor has a native resolution of 1920x1200.
startx -- -logverbose 5
and look in /var/log/Xorg.0.log for lines like
(--) NVIDIA(0): LG L204WT (DFP-0): 135.0 MHz maximum pixel clock
(--) NVIDIA(0): LG L204WT (DFP-0): Internal Single Link TMDS
(--) NVIDIA(0): LG L204WT (DFP-0): Native FlatPanel Scaling is supported
(--) NVIDIA(0): LG L204WT (DFP-0): DFP modes are limited to 60 Hz refresh
(--) NVIDIA(0): rate
Here is 135 Mhz the detected maximum clock for a TMDS encoder on the nvidia card and
(--) NVIDIA(0): EDID maximum pixel clock : 150.0 MHz
is the maximum clock reported by the monitor.
You must check that the fist value in your modeline is below the smaler one of the both clock values (here it is 135 Mhz) or you are risking a hardware damage of your card or monitor.
Then tell the nvidia driver to accept your modeline
Option "ExactModeTimingsDVI" "true"
If you are sure your modeline clock is fine and the nvidia driver is still
rejecting the resolution, you can try
Option "ModeValidation" "NoDFPNativeResolutionCheck"
Nvidia doesn't publish any documentation for their cards and the option
Option "ModeValidation" "NoMaxPClkCheck"
allows to overclock the TMDS encoder on your DVI card
But if the resolution works fine with the nv driver, then probably the maximal clock detection mechanism in the nvidia driver is broken.