I am running Fedora XFCE with an NVIDIA RTX 2080 Ti that is connected via 3 cables to 2 monitors.

Display port is connected twice to the same monitor (for PBP)
HDMI is connected to another monitor

Display Port 1 of my Monitor is the primary screen in XFCE, whereas Display Port 2 of my Monitor is disabled in my XFCE session. However, the login comes before I am a logged in user where the x settings are loaded, so somehow, it is always displayed on Display Port 2.

When I go into the Nvidia settings, I can see that the disabled monitor is DP-0 and the primary monitor is DP-4. However, like I said, in the monitor it's in DP-1 and DP-2, so where does DP-0 and DP-4 come from and why are they reversed? Is there a way to change this easily?

What I tried so far

  • In /etc/lightdm/lightdm.conf added the lines (where dualmon.sh is xrandr --output DP-4 --primary
    • display-setup-script=/usr/bin/dualmon.sh
    • session-setup-script=/usr/bin/dualmon.sh
  • In /etc/lightdm/lightdm-gtk-greeter.conf set active-monitor under the [greeter] section to
    • 0
    • 1
    • 2
    • 3
    • DP-4

None of this worked. The login screen is still displayed on DP-0 (DisplayPort 2) and not on DP-4 (DisplayPort 1)


A few words before: This is probably not a complete solution (but I don't have enough reputation here to write a comment to ask for more input) and you will maybe have to work without GUI for configuration or even temporarily disable your GUI for Linux - so don't be afraid of shell commands (and get familiar with a text mode editor).

The login is driven by the "display manager", so to solve this, you first have to find out, which display manager you are using. Popular choices would be

  • xdm (very basic)
  • gdm (Gnome)
  • lxdm (LXDE display manager)
  • kdm (KDE display manager)
  • lightdm (from Canonical, the makers of Ubuntu Linux)

And there are also lots of others.

To find out, which one you are running, you can have a look into /etc/sysconfig/desktop (RedHat/Fedora specific location!) (according to Is there a simple linux command that will tell me what my display manager is?)

Then you either update your question with the name of the display manager, or dig on by yourself.

On the commandline or in a script you can find out about and configure your monitors with the xrandr tool.

If you installed a standard Fedora installation and switched to XFCE later, there is a good chance that you will use gdm, and maybe also have GUI tools installed to configure it - at least, if you use the default desktop mode (Gnome?) temporarily to do the configuration.

  • I have lightdm (through direct Fedora XFCE install) and found these solutions askubuntu.com/questions/234930/…, however, none of them worked. The one with /etc/lightdm/lightdm.conf didn't change anything. I used this command: xrandr --output DP-4 --primary (DP-4 like I said from xrandr). And the other one in /etc/lightdm/lightdm-gtk-greeter.conf also didn't work. I tried multiple settings for active-monitor. I tried 0, 1, 2, 3 and even DP-4 but none of them worked. My screen is still always black. – Musterknabe Oct 28 '20 at 10:53

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