Problem - no signal with ultrawide display


I have to explain some background information a little with my experience to make my problem understandable:

I have two displays connected to a GeForce RTX 3080Ti video card:

  • 24" 1920x1080 60Hz via DP
  • 34" 3440x1440 144Hz via DP


  • If the 34" display is connected, in case of Debian or Qubes OS, the screen where I could enter the SSD decryption password is not visible, also the loading screen is not visible, etc. The monitor goes dark, I get a “no signal” message. This is true for both Debian and Qubes OS, so I can neither unlock the encryption nor log in to the OS (so I assume this must be a conflict betweenmy Linux and HW setup).
  • If only the 24" display is connected, everything works normally as it should. I can enter the unlock code and log in, etc.
  • If I start the computer with the 24" monitor only, everything is fine, but if I then connect the 34" display as well, I cannot set it the resolution correctly in the Display Settings either. On the 24" display, the mouse pointer is graphically shifted by 10-15 cm compared to its real position (right click → the context menu appears 10-15 cm away), meanwhile, display 34" is dark. If I mirror the 24" display to the 34" display, it turns on but only in the resolution of the smaller monitor, which is obviously not suitable in either proportion or resolution.

What I know and am sure of:

  • I use Windows 10, Qubes OS and Debian, which are installed on their separated, dedicated SSDs.
  • The problem occurs only with Linux distributions, not with Windows.
  • With Debian, I was able to solve the problem by installing the “nvidia-driver”. After that, the 34" display worked flawlessly under Linux.
  • I must have a configuration or driver problem (the nouveau driver does not natively support 3440x1440 resolution, while the nvidia-driver does)

My question:

  • In the case of Qubes OS, how could the nvidia driver be installed under dom0 so that it can be loaded during booting and my 34" monitor always displays the image? A step-by-step help/commands list would be appreciated.

Thank you for your help!

Great description! Thanks.

Have the same issue but only one widescreen display (Samsung Odyssey G9, 5120 x 1440, 240 Hz) connected. It doesn’t work neither with Qubes 4.1.2 nor Qubes 4.2.0-rc1.
I also use Windows 11, Debian 12.1 and Qubes-OS installed on separated, dedicated SSDs.
Graphic card works flawless with Debian 12.1 after installing the ‘nvidia-driver’ package.

Thank’s for your help!