Ubuntu and NVidia Quadro P400

I'm quite new to Linux, but I have to ask about a problem, that was probably asked a zillion times before, since I could not solve it with pure research - sorry for that!

Until Friday 4th of June I was happily running a Ubuntu 18.04 LTS, then probably some update did prevent me from booting and got me a "kernel panic". I don't know how to get a log of that to show it to you.

The system is a HP Z420 machine, SATA-SSD harddrive Crucial M400 (250GB) and NVidia GP107GL [Quadro P400] graphic adapter, all working nicely until that day.

What did I try since then:

• I disabled the splash screen on start.
• I reinstalled Linux and tried three distros: Ubuntu 18.04.5, Ubuntu 20.04.2.0 and Ubuntu Mate 20.04.2.0 (I checked the checksums). I did all updates every time.
• Everything looked good until I tried to invoke a NVidia driver, either of the three ways: additional drivers via GUI, apt-get or via ubuntu-drivers at command line; and every driver 390, 460, 465.
• On every reinstall I have to delete the EFI-partition and add it again and format the partitions for boot and root, otherwise the system will not work.
• After every reboot I get a kernel panic again or, more likely, a black screen (Ubuntu) / grey screen(Ubuntu Mate), probably when the graphical surface should start.
• Then I start all over again.

I did think about buying a new harddrive, but did not do yet.

What else can I do? I am quite desparate now after 10 days of reinstalling again and again.

Add 16 June 2021 / Edit 02 August 2021: I tried to follow NVidias Installation Guide which is not tailored to Ubuntu. I hit Ctr+Alt+F1, moved to runlevel 3, stopped the x-server and blacklisted Nouveau with these commands:

$ sudo telinit 3
$ sudo service lightdm stop
$ sudo bash -c "echo blacklist nouveau > /etc/modprobe.d/blacklist-nvidia-nouveau.conf"
$ sudo bash -c "echo options nouveau modeset=0 >> /etc/modprobe.d/blacklist-nvidia-nouveau.conf"
$ sudo update-initramfs -u
$ sudo telinit 6

After that reboot I tried to install the driver with

$sudo bash NVIDIA-Linux-x86_64-460.80.run

I reboot again. I see some commands running, pass the grey screen, see some more commands running and end with a black screen with a white underscore where the login should be.

Add 18 June 2021 / Edit 02 August 2021: Even the nouveau driver runs unstable, the screen freezes after 3-15 minutes @ a solution of 25xx * 19xx and 60Hz. It is best not to run anything full screen, especially no browser.

I also ordered another grahic adapter to check, but dpd lost it.

Add 02 August 2021: I installed Ubuntu Mate 20.04.2.0 from scratch again with the same image as a month ago, third party software included and the NVidia driver is working right after the install - I am totally stunned! The kernel ist 5.8.0-63-generic. I guess the new Nvidia driver 470 did the trick.

After you have blacklisted the Nouveau driver in the conf file you have to run this command as well:

sudo update-initramfs -u

This will change the system (after a re-boot) so that the nouveau kernel moduke is not running.

You can see which module is running by looking at

lspci -k

I suppose the Nvidia Driver 470 solved my problem.