Yesterday nvidia drivers version 460 were running correctly on my ubuntu 20.04 system with three GTX1070 gpus. Sometime in the early morning hours, the drivers stopped working. I suspect that may have been due to the installation of some kind of system update, but I don’t know what. When I realized that the drivers didn’t appear to be working this morning, I first tried simply rebooting the system, then I tried power it down and turning it back on. Next I started a terminal window and tried running nvidia-smi, and nvidia-smi reported that it could not communicate with the nvidia driver.
I tried resolving that problem by using the ubuntu Software & Updates app to revert to version 450 (no help), then back to version 460 (no help), then to the nouveau driver and back to version 460 (still no help). Then did some googling and based on another thread on this site tried:
sudo apt install nvidia-prime (latest version already installed)
sudo prime-select nvidia (nvidia profile already selected)
sudo ls /lib/modprobe.d/blacklist-nvidia.conf (not found)
sudo update-initramfs -u
Unfortunately, things got worse after that, and the system would no longer boot using the default grub selection. By switching to a prior kernel (5.8.0-49) via grub, the system will boot ok, but the nvidia drivers still don’t appear to be loading. Kernel version 18.104.22.168 is the latest (and default) kernel version installed on my system, but I don’t know when that version was installed and what kernel version(s) were being used over the past week or two since building this system and installing ubuntu, while everything was working correctly.
I next tried adding nvidia-drm.modeset=1 on the end of the GRUB_CMDLINE_LINUX_DEFAULT line in /etc/default/grub, followed by sudo update-grub. But update-grub complains that nvidia-drm.modeset=1 is not found when sourcing /etc/default/grub. Then I tried manually executing sudo nvidia-drm, and that command was not found.
I can run the nvidia-bug-report.sh script if desired, however I wasn’t certain that would be helpful since I am unable to boot my system using the default kernel, so the configuration won’t be the same as for the kernel that is currently booted. I am a linux/ubuntu novice, and really need to get that system back up and running properly, so any help in resolving these issues would be greatly appreciated.