It seems to be a common issue but I could not find a solution.

  • I just clean installed Ubuntu 20.04 Desktop and updated it with the "Software & updates" tool.
  • PC:HP ProDesk 400 G4 Desktop-Mini-PC
  • The monitor attached on one of the DisplayPort ports: HP EliteDisplay E243
  • Video card (lspci -k | grep -A 2 -i "VGA") :

00:02.0 VGA compatible controller: Intel Corporation 8th Gen Core Processor Gaussian Mixture Model
DeviceName: Onboard IGD
Subsystem: Hewlett-Packard Company 8th Gen Core Processor Gaussian Mixture Model

  • output of command seen on other related questions/answers :

xrandr --query
Screen 0: minimum 320 x 200, current 1920 x 1200, maximum 16384 x 16384
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-3 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 59.95*+
1920x1080 60.00
1600x1200 60.00
1680x1050 59.95
1280x1024 60.02
1280x960 60.00
1024x768 60.00
800x600 60.32
640x480 59.94
720x400 70.08
HDMI-3 disconnected (normal left inverted right x axis y axis)


  • The configuration was working out-of-the-box on Windows 10 (on another disk) and Debian 10 Buster (on an usb stick live install).
  • I could not find anything obviously wrong in the dmesg output.
  • I also tried to change grub to add nomodeset it does not make any difference.
  • I tried switching to lightDM (and back to gdm, +reboot) but no difference noticed.
  • I also did an update with sudo apt update ; sudo apt upgrade but no change.
  • I upgraded the kernel to the last stable (5.6.16) and booted on but without effect.

Then I tried reverting to Windows 10 (by switching to the old drive) or Debian 10 (by booting on the live usb stick) but no monitor plug on the DP port is found anymore.

I suppose for the some reason the DP ports have been fried during the Ubuntu install, hence there is probably no solution.

But just in case someone has some tricks to resuscitate the DP port, I thought I should post.
if more info is needed please let me know.