27

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

  • 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 and Debian 10.
  • I could not find anything obviously wrong in the dmesg output.
  • (edit) I also tried to change grub to add nomodeset it does not make any difference.
  • (edit) I tried switching to lightDM (and back to gdm, +reboot) but no difference noticed.
  • (edit) I also did an update with sudo apt update ; sudo apt upgrade but no change.
  • (edit) I upgraded the kernel to the last stable (5.6.16) but without effect.

If some extra info is needed please let me know.

call me Steve
  • 371

6 Answers6

19

Check if you have the latest drivers

sudo ubuntu-drivers autoinstall

Then check for your additional drivers. Try to go to

  • Software & updates
  • Additional Drivers (And there you see your drivers.)
  • Change your card driver then press apply (even if it is a good driver),
  • Then change again to the latest driver.
  • reboot

This resolved my issue, I think ubuntu did not recognize drivers because of some updates.

Hope it helps.

Muhamet Smaili
  • 311
8

Just spent hours trying to fix the same problem. Didn't realize I was using a directional HDMI cable.

Please flip your cables around before going crazy looking for solutions, it may be as easy as that...

Reggie
  • 89
3

I have Ubuntu studio 20.04. I upgraded my ASUS motherboard BIOS and one of my two monitors stopped working. I looked at the output of dmesg and it showed this:
[ 50.822389] Lockdown: Xorg: raw io port access is restricted; see man kernel_lockdown.7

Some googling showed that the BIOS UEFI safe boot locks the kernel and won't allow the Nvidia drivers to load. Dual boot won't work either with a safe boot.

I followed these instructions to remove safe boot: How To Disable Secure Boot on an ASUS Motherboard. After rebooting both monitors were working.

Lorenz Keel
  • 9,511
Stuart Anderson
  • 86
3

I fixed it by upgrading to Ubuntu 20.10 with kernel version 5.8

Aiden Turner
  • 91
2

Faced this problem today. Solved with below steps

  1. Created Ubuntu USB startup disk with ubuntu-21.10-desktop-amd64.iso
  2. Boot USB selected required options and also provided wifi password. Checked Ubuntu updates download and third party software download.
  3. Reached to step where I had to select one of the radio a. Fresh Install 2. along side Ubuntu 20.04 ( my current ). Did not select any option and quit installation from this point and powered off.
  4. Next boot of 20.04 detected my external monitor :-)

Good Luck. Keep sharing tips, trick and solutions and help whenever we can.

Nitin
  • 21
0

I have a similar issue with my Lenovo X1 Carbon Gen6 on 22.10.

My issue is due to the fact that Lenovo upgraded their firmware in a way it disables the Thunderbolt support which seems very tricky to fix (No thunderbolt device anymore in lspci).

https://github.com/fwupd/firmware-lenovo/issues/264

I let this message here in case I'm not the only one ending here

Jean Claveau
  • 121