External Monitor not working. Ubuntu, nvidia

Question

I'm having a precision 7530 with i7-8850H and NVIDIA Quadro P2000 and using ubuntu 18.04. Now after some time the external montior connected over displayport (displayport to hdmi cable, where the displayport goes into the laptop and the hdmi cable into the monitor) stopped working. I'm using this workstation at work with the TB18DC dock, where 2 external montiors are connected and work properly. But at home I do not have any dock and with the setup mentioned above the external monitor stopped working. It did work some months ago. During the time it worked and now I have done normal ubuntu software updates where also the bios-firmware has been updated to 1.5.2 (i'm not sure what version i've had before, was the first time i updated firmware after bought, so maybe 1.0.7?).   I have also installed the nvidia 390 driver.   xrandr says with connected displayport monitor:   Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192 eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm 1920x1080 60.03*+ 60.01 59.97 59.96 59.93 48.02 1680x1050 59.95 59.88 1600x1024 60.17 1400x1050 59.98 1600x900 59.99 59.94 59.95 59.82 1280x1024 60.02 1440x900 59.89 1400x900 59.96 59.88 1280x960 60.00 1440x810 60.00 59.97 1368x768 59.88 59.85 1360x768 59.80 59.96 1280x800 59.99 59.97 59.81 59.91 1152x864 60.00 1280x720 60.00 59.99 59.86 59.74 1024x768 60.04 60.00 960x720 60.00 928x696 60.05 896x672 60.01 1024x576 59.95 59.96 59.90 59.82 960x600 59.93 60.00 960x540 59.96 59.99 59.63 59.82 800x600 60.00 60.32 56.25 840x525 60.01 59.88 864x486 59.92 59.57 800x512 60.17 700x525 59.98 800x450 59.95 59.82 640x512 60.02 720x450 59.89 700x450 59.96 59.88 640x480 60.00 59.94 720x405 59.51 58.99 684x384 59.88 59.85 680x384 59.80 59.96 640x400 59.88 59.98 576x432 60.06 640x360 59.86 59.83 59.84 59.32 512x384 60.00 512x288 60.00 59.92 480x270 59.63 59.82 400x300 60.32 56.34 432x243 59.92 59.57 320x240 60.05 360x202 59.51 59.13 320x180 59.84 59.32 DP-1 disconnected (normal left inverted right x axis y axis) DP-2 disconnected (normal left inverted right x axis y axis) HDMI-1 disconnected (normal left inverted right x axis y axis) DP-3 disconnected (normal left inverted right x axis y axis)      I have also tried the following: installing lightdm and use it (no effect) disable switchable graphics in bios (no effect) downgrade firmware version-by-version till 1.2.5 (as it won't let me downgrade back to 1.0.7. no effect) reset bios settings to default (no effect) reinstalling nvidia-driver (no effect) trying without any nvidia-driver (no effect)   I booted from a live ubuntu usb stick and without external montior it worked normally but with external monitor I got the following error message:   Any ideas how to get the monitor working? Thank!

pomm0 · Answer

I got it working thanks to this mans hint at askubuntu forum:

I recently installed the nvidia-418 driver on my laptop which uses Ubuntu 18.04. At first the external monitor worked perfectly, but after I switched from power saving mode (sudo prime-select intel) back to performance mode (sudo prime-select nvidia), the second monitor was not detected anymore.

I discovered that prime-select writes a configuration file which causes the problem. It enables the nvidia-drm modeset option. You can simply undo the change made by prime-select by commenting out this option. It will not be reset, because prime-select only writes this file when it does not yet exists.

Open the file in your favorite editor (vim, nano, gedit, etc.).
sudo nano /lib/modprobe.d/nvidia-kms.conf
And comment out the the nvidia-drm modeset option.
# This file was generated by nvidia-prime
# Set value to 0 to disable modesetting
# options nvidia-drm modeset=1
Hope this also helps you and many others!

ps: It is completely normal that the second monitor is not detected in power saving mode when the connection is part of the nvidia graphics card.

andrewbanach · Answer

I'm running into the same issue on my 7530.  Has this problem been solved?  Does Dell's ubuntu 18.04 LTS image support external monitors?  I installed 18.10 via desktop image from canonical.

akashvermaofskt · Answer

Spoiler pomm0 solutions works.Thankyou pomm0 solutions works.Thankyou

kkaland · Answer

I can't believe this worked, but it did! Thank you! Another thing to note for 18.04 users is that monitors connected over USB-C are supported from kernel 4.19+, so you should use the latest kernel (it was just updated to 5.0.x).

dmandb · Answer

I create an account here just to say thank you, this is exactly what solved my problem. Thanks!

filip1 · Answer

I have the same problem with mi Precision 7530.

Vadim775 · Answer

It is the same for me: there is no mentioned file in  /lib/modprobe.d/  and nvidia-settings is not able to save a custom config file

remyvrs · Answer

... it works! Thanks a lot !

dirschn · Answer

I created this account (on a thinkpad no less) just to thank you for this, I was getting really worried it would be a super complicated obnoxious process and you got it fixed in literal seconds. Thank you!

inspy · Answer

Same problem here... this solution doesn't work for me neither.

RomitZunjarrao · Answer

I have no such file

onemoar · Answer

bump did the trick on my e6430/mint 19.1 install

nani0204 · Answer

After disabling the secure boot int the bios  menu ,My laptop dell g3 3579 has connected to external monitor.

trampen · Answer

Thank you very much. It helped me Regards, Marek

stephano-cell · Answer

I have same issue, the file does not exist. Have you found a solution?

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