External Monitor not working. Ubuntu, nvidia
I recently installed the nvidia-418 driver on my laptop which uses Ubuntu 18.04. At first the external monitor worked perfectly, but after I switched from power saving mode (sudo prime-select intel) back to performance mode (sudo prime-select nvidia), the second monitor was not detected anymore.
I discovered that prime-select writes a configuration file which causes the problem. It enables the nvidia-drm modeset option. You can simply undo the change made by prime-select by commenting out this option. It will not be reset, because prime-select only writes this file when it does not yet exists.
Open the file in your favorite editor (vim, nano, gedit, etc.).
sudo nano /lib/modprobe.d/nvidia-kms.conf
And comment out the the nvidia-drm modeset option.
# This file was generated by nvidia-prime
# Set value to 0 to disable modesetting
# options nvidia-drm modeset=1
Hope this also helps you and many others!
ps: It is completely normal that the second monitor is not detected in power saving mode when the connection is part of the nvidia graphics card.
I do prefer the solution by thomasnabgelis, but other working solution would be to use lightdm display manager. To do this just run
sudo apt-get install lightdm
and
sudo dpkg-reconfigure lightdm
if not configured after install.
Why this happens? I spent a lot of time trying to understand... nvidia-drm provides anti-tearing solution, though I didn't find any difference with this turning that off. Citation from nvidia forum (topic):
nvidia-drm modeset=1 is needed for tear-free display but since this is enabling linux kms for the nvidia driver, gdm thinks it can use wayland. Having a parallel wayland session makes it somehow impossible for X to detect any outputs on the nvidia gpu
Thanks for all your hints. My second monitor was dead a couple of days ago. I got it working again with the following steps:
- sudo nvidia-settings -> if this shows an error, then the nvidia driver is not active
- settings > info > software > additional drivers -> switch to current (or not so current) version of nvidia driver. If there is no error, skip step 3.
- install missing nvidia-drivers: sudo apt install nvidia-driver-450 (or similar)
- reboot
- it works (at least for me)
Hope that helps anyone. Cheers, Werner
I scoured the web when I got my MSI GS65 Stealth with GeForce GTX 1660 Ti/PCIe/SSE2 and installed Ubuntu 18.04. I tried pretty much everything but nothing helped.
What did it for me was installning Ubuntu 19.10. Everything worked right out of the box and seeing as Ubuntu 20.04 LTS is right around the corner, this feels like a viable solution.