How to switch to a particular resolution? Xorg complains "No valid modes for "DFP-1:2560x1600"; removing." and ignores my setting.

[Chris Sorenson]

> On 9/23/20 1:35 PM, Yuri wrote:
> > On 2020-09-23 08:21, Pete Wright wrote:
> > > $ xrandr |grep 2560
> >
> >
> > Interestingly, this command shows nothing after Xorg was started,
> > but shows 2560x1600 after the "NVidia settings" program changes
> > the resolution to 2560x1600.
> >
> > I just need to find a way, if any, to do this automatically.
> >
> 
> I think we need a better picture of what's actually connected to
> your system and what it's reporting itself as capable of. The full
> output of xrandr would help, and it would also help to add
> 
> Option "ModeDebug"
> 
> to the "Device" or "Screen" section of /etc/X11/xorg.conf, restart
> the X server, and the attach /var/log/Xorg.0.log.
> 

Also, and sorry to be so blatantly obvious, but are you sure the Nvidia 
kernel module is running?

('lsmod' will tell you)...