modeset(0): Modeline "1680x1050"x0.0

[Chris]

On Fri, 2018-11-23 at 14:46 +0100, Liam Proven wrote:
> > 
> > The DisplayPort (PC) -> DVI (Monitor) made absolutely no difference
> 
> Oh dear. I'm sorry to hear that. Can you at least see a sharper
> image?
> I can tell the difference between an LCD over VGA and over a digital
> connection, and my eyes are poor.
To be honest no I can't tell the difference however my eyes aren't the
greatest either. Possibly if I tried a different Gnome theme I'd be
able to.
> 
> > Guess I'm stuck with it unless someone else with this has an
> > answer.
> > Personally I just don't like something in my syslog that I can't
> > figure
> > out why it's there.
> 
> I sympathise but I fear you are...
> 
> Silly question. You *did* remove the VGA cable, right?
Yep :)
> 
> Another one springs to mind: does the monitor have the ability to
> autosense which port it's connected by? If so, you might want to turn
> that off. Perhaps the current port drops out for a fraction of a
> second while it scans the other ones, and that makes Linux re-detect
> it...
That I'm not sure of however the question comes to mind that why did
this only start when I upgraded from 16.04.5LTS to 18.04.1LTS? In fact
it started as soon as I booted into the new version. 

Do you see anything in the ~/.local/share/xorg/Xorg.0.log - 
https://pastebin.com/xdP4GY6G that could be the cause?

-- 
Chris
31.11972; -97.90167 (Elev. 1092 ft)
08:25:28 up 1 day, 16:05, 1 user, load average: 0.94, 0.92, 0.75
Description:	Ubuntu 18.04.1 LTS, kernel 4.15.0-39-generic