Step-by-step – Nvidia Driver 340 Installation in Debian Bullseye

Installing

2. 2. Enabling Non-free Repo

   How to Add Debian Non Free Repo Preserving System

   contrib & non-free Repos Setup Guide

   Link to Step by step Debian Non Free Repository Setup Guide

3. 3. Installing NVIDIA Driver 340

   Then to Install NVIDIA Driver 340 Debian 11 Driver
   Possibly now see How to Check NVIDIA Graphics Card Model Supported Drivers.
   And again before Setting it up you may Verify which is the Minimum Driver version to Support your Card on: NVIDIA Driver support Website!
   Now to Setup it play:

   sudo apt install nvidia-legacy-340xx-driver nvidia-settings-legacy-340xx

   Authenticate with the User Admin Pass.
   If some Issues then See the Readme file on Bottom…
   And Possibly to Configure the X Server after Setup run:

   nvidia-xconfig

   Last, to Load your barely New Graphics Driver Reboot with:

   sudo reboot