I recently a fresh install of Ubuntu 18.04, with a GTX 1070. Everything works great, except after coming out of suspend, my DisplayPort monitor does not come back, only the HDMI monitor. If I reboot, both monitors are recognized again (with the DP monitor as the primary, and HDMI as secondary).
The graphics card knows the DP monitor is there, because it does turn it on. But as soon as the system resumes, the DP monitor turns back off, and only the HDMI monitor is working.
I installed the graphics drivers using:
sudo ubuntu-drivers autoinstall

  • 1
    Try unplugging and replugging the DP cable next time. I have to do that occasionally with Thunderbolt. Apr 23, 2018 at 22:00
  • It's easier to reboot than climb around behind my desk and try to get to the cables. If there is no solution, I'll just not use suspend and leave the PC on. Apr 23, 2018 at 22:26
  • Oh I thought you had a laptop. Most people with PC's just lock and dim the screen. Apr 23, 2018 at 23:52
  • not turning off your PC is a terrible recommendation to anyone and "most people" really only refers to US citizens or people who don't pay for their electricity bill themselves. A well configured PC should turn on and off just fine and preferably do so quickly. Suspend to RAM is a good compromise, giving near instant boot while consuming a fraction of the power. Jun 15, 2018 at 8:00
  • This solution of overriding the ACPI_OS value worked for me: iam.tj/prototype/enhancements/Windows-acpi_osi.html (found by way of this post: forums.developer.nvidia.com/t/…) Aug 17, 2020 at 17:15


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