Llvmpipe (LLVM 12.0.0, 256 bits) instead of NVIDIA RTX 4080 on ubuntu 20.04

I’am trying to use the Nvidia graphic on my dual boot ubuntu 20.04.
i’am using NVIDIA driver metapackage from nvidia-driver-535 (proprietary), but of the ubuntu information seems that I am using llvmpipe (LLVM 12.0.0, 256 bits). Moreover I can not connect a second monitor.

here the result of nvidia-bug-report.sh
nvidia-bug-report.log (268.1 KB)

The problem I had is similar to this post https://forums.developer.nvidia.com/t/llvmpipe-llvm-12-0-0-256-bits-instead-of-nvidia-rtx-3050-on-ubuntu-20-04/281996/1. I followed the suggestion but it did not work. Could anyone help me fix this issue?

Rather try NVIDIA RTX 4060 not working with Ubuntu 20.04 LTS - #3 by Mart and its folowing post.