Hi and welcome to the forum
- Provide your configuration inside a code block here as explained in that article at top of my reply.
- Where exactly are you saving the configuration (provide the exact pathname)
- How exactly are you making the Xserver load that configuration.
You could try to add these in the [Device]
section of your xconfig:
Option "ModeValidation" "AllowNonEdidModes"
Option "ModeDebug" "true"
The first will allow to use modes that are not provided by the EDID of your monitor.
The second will log all modes the xserver is considering and/or using inside the /var/log/Xorg.0.log
file.
More flags that you can check are in the documentation that is installed together with your driver under /usr/share/doc/nvidia