Problem with Nvidia GeForce 820m driver Ubuntu 20.04

I have a laptop Dell Inspiron-3542 with Nvidia GeForce 820m & an Intel HD 4400 (I don't want to use it).

I want to use only Nvidia with the last updated driver supported by GeForce 820m.

When I use nvidia-340 it works, not very well but it works like:

• The problem with nvidia-340 that it is outdated & I can't use it to play 3d games and does not support DXVK & Vulkan. When I try to open Lutris I got this:

The problem is that I can't use a driver more updated than 340. Any other driver I have tried to install it doesn't work, and the system returns to Intel HD instead of Nvidia. I have tried to add repositories from: https://launchpad.net/~graphics-drivers/+archive/ubuntu/ppa and I got drivers like :

If I install 450 or 450 the system returns to HD graphic If I check drivers list I got:

If i try to install other version directly like 390, it is refused from the system. I got this result:

I have read a lot of topics & saw many videos but haven't found a solution. Does anyone have a solution for my problem?

Install the package nvidia-384 and you'll get the 390. As its description (https://packages.ubuntu.com/focal/nvidia-384) says, the 384 is a "transitional package for nvidia-driver-390".

I too have the 820M, and on a very similar laptop, the Inspiron 3442.