Linux Mint 20, Laptop With Nvidia Card: Can't Get Second Monitor to Work

Question

Let me start by saying that on Linux Mint 18 I had this exact same hardware: same laptop, and same two monitors plugged into it. The laptop has an Nvidia GTX870M graphics card, which is a sort of combination card that works in tandem with the on-board Intel graphics card. Previously I was able to run both monitors from the laptop just fine.

However, now that I've installed Linux Mint 20, only one monitor (and the laptop display) works. I've tried various drivers:

• using the built-in Nouveau drivers
  • works and I can see the second monitor in "Displays" ... but when I enable it my computer crashes
• installing nvidia-driver-390
  • works, but no second monitor
• installing nvidia-driver-418 (recommended by Nvidia)
  • sort of works, but I need to add nomodeset otherwise I boot into a black screen with blinking cursor (and even with nomodeset only one monitor works), and it can only mirror the screen
• installing the Nvidia drivers (418) from NVidia directly
  • this worked, but I couldn't run nvidia-settings, and it seems even the Nvidia people discourage installing this way now

I've also tried other versions without luck. I --uninstalled the manual installation, and I'm doing apt-get purge *nvidia* in-between each.

I've also tried using both bumlbebee and nvidia-prime (and even both at the same time, although apparently that isn't even supposed to work). It seems to have no effect: even when I use prime-select intel I still can't use the second monitor (the one presumably controlled by the Intel card).

I've also tried wiping my xorg.conf, and generating a new one using nvidia-settings -r and that X-Windows command: none of them seem to help. Meanwhile when I try to use the graphical Nvidia settings tool, it either shows up completely empty, or with just a PRIME profiles tab, depending on which drivers I use. There's no way to ever use this tool to configure things.

So in conclusion, I can get the best results with the 390 driver, getting an independent laptop and monitor, but even with it I can't get the second monitor to work. Can anyone help?

Answer 1

I am not using Mint, but I saw some complains concerning very similar problems on Mint Support Forum.

Before trying any potential solution below, I advise you to choose the driver you want to use and stick with it until the end of all your tentatives. Ideally Nvidia-driver-418 should do the trick.

Option 1) It seems there is already out version 4.6.3 that should have fixed some bugs concerning multi monitors. Check if you can upgrade.

Option 2) The workaround useful for at least one of the users was to downgrade from cinnamon-desktop package version 4.6.2-2 (stock) to 4.4.1-2, until the issue is fixed. On Mint to downgrade a package you need to use apt-get on the command prompt. As I have not a running installation I cannot test but the procedure should be similar to:

sudo apt-cache showpkg cinnamon-desktop

it should show you a list of versions available. If you see the earlier version listed, you can request the downgrade with this command:

sudo apt-get install cinnamon-desktop=< put here the cinnamon desktop version available>

Option 3) Another workaround is to install some packages prepared by the maintainer of cinnamon. Here you find the link for those packages. You should download the fine, extract the packages and install the ones suggest with dpkg tool. There is good explanation on how to use this tool here.

I hope this helps you. It is possible that at least this time Nvidia is not the culprit...