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Not a complete newbie to Ubuntu/Linux, but very new to setting it up from scratch. My problem: I am having difficulties getting my second monitor to activate/extend my desktop

Procedure:

After a fresh install of Ubuntu. NVIDIA X Server Settings recognizes that both Nvidia cards are there and recognizes that there are two monitors. However, one monitor is disabled.

Step 1: I activate the second monitor, and by consequence have have to have NVidia generate a X Configuration file at /etc/X11/xorg.conf. Reboot. Result: Both screens are active, but newly active screen is black, and when I move a mouse over it, it changes to an "X".

My understanding is that this is because I haven't activated xinerama yet to extend the desktop to the second display. (according to: Dual GPU, Dual monitor: second monitor black with a shadow of the mouse)

Step 2: I go back into NVidia Server Settings, enable xinerama, overwrite xorg.conf, and run sudo service gdm restart Result: Both screens turn black. I can move the mouse to the other screen and it no longer turns into an "X", but everything is just black.

From here, when I try to use Ctrl+Alt+F2 to get to terminal to undo the problem, the second monitor turns off, the first monitor changes to a flashing underscore cursor, but no terminal prompt and typing on the keyboard is unresponsive. When I reboot, I get the same thing - no login screen, just a black screen with a mouse.

To get back to a functioning PC, I have to Reboot->GRUB->Recovery->(Root)Drop to shell->Replace the xorg.conf with the previous version.

I'm attaching below both the working xorg.conf (from post step 1) and the failing xorg.conf (from post step 2).

Setup:

  • Fresh install of Ubuntu 19.10 (64-bit)
  • NVidia Driver version: 435.21 (this is the one 'recommended' by Ubuntu)
  • GPU 0 and 1 are both: GeForce GTX 980

xorg.conf after step 1: https://pastebin.com/3MzvM2ft

xorg.conf after step 2: https://pastebin.com/fNBWScpp

lshw: https://pastebin.com/Q8GyTFpw

Other things I have tried:

  • Taking the xorg.conf from step 1 and editing it myself rather than having nvidia generate it for me. When I change only the xinerama entry from 0 to 1, I obtain same result
  • Doing step 2, but also setting the "Force Full Composition Pipeline" setting in the advanced settings (suggested at: https://forum.level1techs.com/t/nvidia-xinerama-not-working-ubuntu/131391) - same result
  • Backing down to Nouveau works just fine... by default both monitors appear and the second monitor extends the desktop from the first.

Takeaway: The driver itself seems to be working fine as far as I can tell. Most of the message board posts about this black screen issue seem to be about the drivers themselves... However, my issue seems to be triggered by Xinerama (at least in conjunction with the nvidia drivers). Do you have any suggestions on how to approach this?

1 Answer 1

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I have the same problem, and as soon as both monitors were plugged into the same card it worked.

hope that helps.

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