If you have an AMD Ryzen CPU paired with nVidia GPU you will run into some problems as Ubuntu does not play well with this pairing. In order to remedy this you have to tweak configs a bit by yourself.
Cause of the problem: Ubuntu’s prime-select feature still does not work for AMD/nVidia pairing and requires manual tweaking, it works only for Intel/nVidia pairing.
Modify /etc/X11/xorg.conf if exists, or create if it does not
sudo nano /etc/X11/xorg.conf
Inside paste the following
sudo nano /usr/share/X11/xorg.conf.d/10-amdgpu.conf
Modify OutputClass of /usr/share/X11/xorg.conf.d/10-nvidia.conf
sudo nano /usr/share/X11/xorg.conf.d/10-nvidia.conf
Option "PrimaryGPU" "Yes"
Caution! This step needs to be repeated after every nVidia driver update.
Create two files named optimus.desktop in the following locations
sudo nano /etc/xdg/autostart/optimus.desktop
sudo nano /usr/share/gdm/greeter/autostart/optimus.desktop
Inside both paste the following
Exec=sh -c "xrandr --setprovideroutputsource modesetting NVIDIA-0; xrandr --auto"
Caution! Exec… line is long, make sure it is actually one line
After all files have been modified correctly – reboot
Greeter displayed on the wrong screen
Caution! If you have the auxiliary display plugged in, greeter might be displayed only on the auxiliary monitor! Mouse movement can be restricted to that monitor as well!
- Open Ubuntu Settings
- Navigate to Displays
- Select Single Display option
- Set Primary Display to 1 Built-in display
- Click Apply
- You should have only your laptop display working right now
- Go back to Displays settings and set them however you like now
- Displays should work correctly now
- To force greeter on built-in display open terminal and run the following
sudo cp monitors.xml /var/lib/gdm3/.config/
Now everything should be set-up correctly