#StackBounty: #dual-boot #grub2 #nvidia #multiple-monitors Can't Boot on Dual Monitor

Bounty: 50

Summary of issue: Can’t see GRUB2 boot menu on monitor connected via DVI port.

Up until recently I had everything working fine for my Windows 10 / Ubuntu 18.04.2 dual boot setup. I had two monitors: one connected to HDMI and the other to Displayport on graphics card and using a Display-Port -> DVI cable to plug into second monitor. My primary monitor was the one connected over HDMI.

The monitor that I had plugged into HDMI failed and I bought a new one. To make the most of my new monitor, I want to connect it over Displayport. This means my 2nd monitor is now connected DVI-D to DVI-D.

Given the priority order of GPU (GTX 1050 Ti) is DVI, HDMI, Displayport this means that for booting my old 2nd monitor is now primary before the OS is loaded.

However, I am unable to see the dual boot menu. Instead I see a few lines of coloured pixels at the top of my 2nd monitor (the one connected via DVI).

Windows boot works fine (if I change BIOS to boot straight to Windows). However, the only way I can access Linux is to unplug my 2nd monitor. Then the Displayport monitor is the only one and everything works fine. Once into Linux I can then plug in the second monitor to the DVI cable and it is recognised and works.

I have tried the following (incrementally and individually):

  • Set GRUB_GFXMODE to 640×480
  • Set GRUB_TERMINAL to console
  • Changed display driver to NVIDIA rather than Linux default

Note that after updating the GRUB2 settings in /etc/default/grub I have ran the grub update. I can see the changes have taken effect when I boot with 2nd monitor unplugged.

This has me tearing my hair out – any suggestions very welcome. If I’ve ommitted any key information, please comment.

UPDATE 1

I have tried booting from a Linux boot USB. I see the same result (i.e. a few coloured lines of pixels at top of screen). Is GRUB2 compatible with DVI-D?


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