NVIDIA RTX 3080 GPU not working with Ubuntu 20.04, Kernel 5.8.0-50-generic

Question

I recently created a dual-boot on my Asus ROG STRIX Scar 15 w/ NVIDIA RTX 3080 GPU. I had some issues installing Ubuntu 20.04.2 LTS, but finally got it to work, however, my GPU is not coming up when I look for it in Terminal.

Looking at the ubuntu-drivers devices I get:

:~$ ubuntu-drivers devices
== /sys/devices/pci0000:00/0000:00:01.1/0000:01:00.0 ==
modalias : pci:v000010DEd0000249Csv00001043sd00001602bc03sc00i00
vendor   : NVIDIA Corporation
driver   : nvidia-driver-460 - third-party non-free recommended
driver   : nvidia-driver-460-server - distro non-free
driver   : nvidia-driver-465 - third-party non-free
driver   : xserver-xorg-video-nouveau - distro free builtin

I tried purging nvidia, reinstalling, rebooting, etc. but nothing seems to work. When I go into my Ubuntu settings the GPU that is shown is: llvmpipe (LLVM 11.0.0, 256 bits).

When I try lspci | grep VGA I get:

01:00.0 VGA compatible controller: NVIDIA Corporation Device 249c (rev a1)
05:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Device 1638 (rev c5)

Additionally, when I try nvidia-smi I get "NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running."

When I try nvidia-settings I get:

ERROR: NVIDIA driver is not loaded


ERROR: Unable to load info from any available system


(nvidia-settings:5634): GLib-GObject-CRITICAL **: 15:28:57.073: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
** Message: 15:28:57.075: PRIME: No offloading required. Abort
** Message: 15:28:57.075: PRIME: is it supported? no

When I type prime-select query the only item is nvidia (which used to show nothing but ondemand).

I tried downloading from the nvidia site with the .run file, I tried autoinstall, I tried prime-select intel then reboot then back to prime select-nvidia, but nvidia-smi and nvidia-settings still fails.

Please help!

Additional Info:

When I try sudo lshw -C video I get

*-display UNCLAIMED       
       description: VGA compatible controller
       product: NVIDIA Corporation
       vendor: NVIDIA Corporation
       physical id: 0
       bus info: pci@0000:01:00.0
       version: a1
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress vga_controller cap_list
       configuration: latency=0
       resources: iomemory:f80-f7f iomemory:fc0-fbf memory:fb000000-fbffffff memory:f800000000-fbffffffff memory:fc00000000-fc01ffffff ioport:f000(size=128) memory:fc000000-fc07ffff
  *-display UNCLAIMED
       description: VGA compatible controller
       product: Advanced Micro Devices, Inc. [AMD/ATI]
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci@0000:05:00.0
       version: c5
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi msix vga_controller bus_master cap_list
       configuration: latency=0
       resources: iomemory:fc0-fbf iomemory:fc0-fbf memory:fc10000000-fc1fffffff memory:fc20000000-fc201fffff ioport:d000(size=256) memory:fc500000-fc57ffff

which doesnt seem right to me?

My monitor will also not work in Linux, which also seems to have something to do with the GPU.

Solution

I fixed this by first reinstalling Ubuntu 21.04. (I knew this was a step in the right direction because my monitor finally started working!)

Once Ubuntu 21.04 was installed, I first tried reinstalling the nvidia drivers using the Software & Updates, then rebooting to disable secure boot. When I disabled secure boot, it still wouldn't boot, so I re-enabled secure boot, did prime-select intel, then purged Nvidia similar to this (https://forums.developer.nvidia.com/t/newly-installed-drivers-are-not-found-when-nvidia-smi-is-called/82686/7).

I rebooted, I disabled secure boot, it finally booted. However, when I tried to install the Nvidia drivers using Software & Updates it would not boot again with Secure Boot disabled.

I discovered I had to install the Nvidia drivers using terminal ubuntu-drivers autoinstall

Thus, the procedure was

1. Install Ubuntu 21.04
2. prime-select intel
3. purge nvidia drivers

sudo apt-get remove --purge '^nvidia-.*'
sudo apt-get install ubuntu-desktop
sudo apt-get --purge remove "*cublas*" "cuda*"
sudo apt-get --purge remove "*nvidia*"
sudo add-apt-repository --remove ppa:graphics-drivers/ppa
sudo rm /etc/X11/xorg.conf
sudo apt autoremove
sudo reboot

4. Reboot, disable secure boot in BIOS
5. Reinstall Nvidia as such

sudo ubuntu-drivers devices
sudo ubuntu-drivers autoinstall
sudo reboot 

I have yet to re-enable secure boot as I am scared that it will not boot and I will have to go through this process again.