Ubuntu 18.04: Low screen resolution after Nvidia driver installation
OK, I solved it. I uninstalled the NVidia drivers and used Nouvea. Had I known that was possible to start with I would have done so as I didn't want any of the NVidia features as such, just dual monitor support.
For anyone interested in the final approach here it is. Please note that these notes are specific to my devices, so you will need to change the names of the devices in the following commands.
In terminal:
xrandr
This will give you and output which shows all the graphics outputs available and their supported resolutions. You should see that HDMI-1 is connected and supports 2560x1440 resolution. And that DVI-I-1-2 (or similar) is also connected, but only supports 1920x1080 So we need to get DVI-I-1-2 to also support 2560x1440
To do this we need to use xrandr to add another profile for the 2560x1440 resolution and then apply that to DVI-I-1-2. Again in terminal:
cvt 2560 1440 60
This will get you the "modeline" that you need to use to do this.
Currently that line is:
"2560x1440_60.00" 312.25 2560 2752 3024 3488 1440 1443 1448 1493 -hsync +vsync
Construct the following from that to add the new mode:
xrandr --newmode "2560x1440_60.00" 312.25 2560 2752 3024 3488 1440 1443 1448 1493 -hsync +vsync
And then add the mode to DVI-I-2
xrandr --addmode DVI-I-2 2560x1440_60.00
You should now be able to go to your NORMAL display settings and select the higher resolution for each monitor.
However, this won't persist between user sessions, so you need to resolve that.
Create an .xprofile file which will be executed automatically every time Ubuntu boots (check if it exists before doing this). And set it to have execute permissions:
touch $HOME/.xprofile
chmod +x $HOME/.xprofile
Copy and paste the two lines from above into that file:
xrandr --newmode "2560x1440_60.00" 312.25 2560 2752 3024 3488 1440 1443 1448 1493 -hsync +vsync
xrandr --addmode DVI-I-2 2560x1440_60.00
You will now have the full resolution on both monitors on re-boot.