Tama. Thanks so much. Great guide. Needed to change kernel to 58 and had to use a different driver for my card (450.80.02) for a Geoforce 1050 ti. You don't say anything about backport/header installation. Did you do this before this driver install or does this do it automatically?
I mentioned in my first comment:
My Openmediavault System is OMV5.3.9-1 with Linux 5.4.0-0.bpo.-amd64 kernel and NVIDIA GeForce GTX1660. Plex hardware transcoding works for me based on the following (If Plex doesn't hardware transcode, check this video) :
Step 1: Install the NVIDIA driver based on the second option (How to install NVIDIA driver by using the official nvidia.com package step by step instructions).
(If you are installing another bpo kernel, you will need to reinstall the Nvidia driver compilation prerequisite: apt -y install linux-headers-$(uname -r) )
in this comment shows the "omv.jpg" & "linux-headers.jpg".
Currently, My Openmediavault System is OMV5.5.20-1 with Linux 5.9.0-0.bpo.2-amd64 kernel, NVIDIA Linux Graphics Driver 455.45.01 (Linux Short Lived (Kernel 5.9 support)) and NVIDIA GeForce GTX1660. Works well