Get rid of XOrg processes

I am running a Workstation with two GPU boards. One older AMD board connected to my screens and a Tesla K80 for CUDA development. After installing Kubuntu 21.10 I have some problems like kernel launch timeouts and failed launches. Also I can not reset the K80 since two XOrg process are running. Since I use the K80 for CUDA only I guess I do not need those processes.

I checked the drivers. In the “Additional Drivers” settings tool the latest nvidia-driver-470 and not the Xorg Nouveau driver is installed.
I also found some “NVIDIA XServer settings” application that lists my K80. I don’t know which package installed that application but anyway it seems to provide no relevant settings.

My questions:

  1. Where do those Xorg processes come from?
  2. Is there any sense in running Xorg processes for a CUDA-only card?
  3. How can I get rid of those processes permanently and how can I tell Xorg not to use my Tesla for Graphics output?