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18.04 on an Asus Z97.

On boot, the monitor works fine and gets as far as displaying the Ubuntu splash screen (Ubuntu plus the dots). After that the display loses the signal. I have vino running and remote desktop works fine.

I've tried both HDMI and DVI, and both an Elecrow 1080p and an old Viewsonic monitor. Every time, the signal is lost at the same point. I've tried various screen resolutions but no difference.

From the remote desktop, display settings shows 'unknown monitor'.

I'm running gdm3 as I was never able to get lightdm running on this system. I just tried it again and it fails to create a display so I can't even get a remote desktop. I can still log in with putty though.

I tried some of the solutions here: External monitor not detected on Ubuntu 18.04 but no luck.

With gdm3:

xrandr: Failed to get size of gamma for output default Screen 0: minimum 320 x 240, current 1600 x 1200, maximum 1920 x 1200 default connected primary 1600x1200+0+0 0mm x 0mm 1600x1200 60.00* 70.00 65.00
1920x1200 60.00
1920x1080 60.00
1680x1050 70.00 60.00
1400x1050 70.00 60.00
1600x900 60.00
1280x1024 60.00
1440x900 60.00
1400x900 60.00
1280x960 60.00
1440x810 60.00
1368x768 60.00
1360x768 60.00
1280x800 60.00
1152x864 70.00 60.00
1280x720 60.00
1024x768 70.00 60.00
960x720 60.00
928x696 60.00
896x672 60.00
1024x576 60.00
960x600 60.00
960x540 60.00
800x600 70.00 65.00 60.00 56.00
840x525 70.00 60.00
700x525 70.00 60.00
800x450 60.00
640x512 60.00
720x450 60.00
700x450 60.00
640x480 60.00
684x384 60.00
680x384 60.00
640x400 60.00
576x432 70.00 60.00
640x360 60.00
512x384 70.00 60.00
512x288 60.00
480x270 60.00
400x300 60.00 56.00
320x240 60.00

I have a couple of other linux systems where everything just works so I'm thinking this is a driver issue but I have no idea what to do about it.

Any ideas?

Rob.

2 Answers 2

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In the recovery terminal, or if you can connect remotely, try adding nomodeset to your grub configuration:

sudo sed -i "s|quiet splash|quiet nomodeset splash|g" /usr/share/grub/default/grub
sudo update-grub

This will change the line in /usr/share/grub/default/grub

From...

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

To...

GRUB_CMDLINE_LINUX_DEFAULT="quiet nomodeset splash"

This instructs the kernel to not load video drivers and use BIOS modes instead until X is loaded.

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  • Thanks but it didn't make any difference.
    – Rob190
    Jun 6, 2020 at 8:57
  • Just to confirm, my grub file is now: GRUB_DEFAULT=0 GRUB_TIMEOUT_STYLE=hidden GRUB_TIMEOUT=0 GRUB_DISTRIBUTOR=lsb_release -i -s 2> /dev/null || echo Debian GRUB_CMDLINE_LINUX_DEFAULT="quiet nomodeset splash" GRUB_CMDLINE_LINUX=""
    – Rob190
    Jun 6, 2020 at 11:55
  • That looks right. Since this didn't work, you can revert to the original using sudo sed -i "s|quiet nomodeset splash|quiet splash|g" /usr/share/grub/default/grub. Remember to execute sudo update-grub after making any changes to your grub configuration.
    – Enterprise
    Jun 6, 2020 at 16:26
  • I don't have any other suggestions. If you haven't already looked at this, perhaps it will help?... askubuntu.com/questions/162075/…
    – Enterprise
    Jun 6, 2020 at 16:28
  • 1
    Thanks for trying. I think the answer is to move on from 18.04 as soon as I can. It's been a very painful experience (2 out of 3 upgrades to it failed and resulted in unbootable systems, continuing problems with NFS, LAN drop-outs, desktop freezes etc. etc.) Wish I'd stayed with 14.04. That was a good vintage :-).
    – Rob190
    Jun 10, 2020 at 9:55
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Update: I wasn't able to get the display working in 18.04. I eventually upgraded to 20.04 (clean install) and although I was able to get a signal this time, the display was badly corrupted (looked like a line sync problem). The BIOS slash screen was always OK but the purple Ubuntu screen never displayed properly. I tried 3 different monitors and none of them worked although they all displayed differently. I cured the problem by installing an old NVidia GPU and disabling the on-board graphics (it's an Intel Skylake).

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