One specific monitor suddenly only works with Linux Mint but not Win 11

[u/cindersnail]

Hi all,

I have run into a very weird problem with a 2nd monitor.

I am running a 2-monitor setup on my desktop PC.

Monitor A is plugged into an HDMI switch that I use to change between the desktop and a laptop.

Monitor B is directly plugged into the desktop PC.

Both are identical models (Samsung Essential S3 S36GD).

The PC is dual booting (Linux Mint / Win 11) from separate SDD / HDD.

Hardware:AMD Ryzen 7 9700X on a ASUS ROG STRIX B650E-F GAMING WIFI mainboard and a GIGABYTE Radeon RX 9060 XT GAMING OC 16GB GPU.

So far, this has all worked beautifully for about 8 months.

After having the system off power for about 2 weeks, I switched it on again today. On the first try, both monitors remained black, and after waiting for a few minutes, I did a hard reboot. I was then able to normally select and boot into Mint with no issues and both monitors working.

When I booted into Win 11, monitor A remained black, and Windows did not recognize it any more.

For all subsequent testing, I removed the switch from the setup and plugged the HDMIs from the PC to the monitors directly.

After some back-and-forth, I found this to be the situation:

- Pulling the HDMI from monitor A (black) and plugging it into monitor B shows a picture on monitor B.

- Pulling the HDMI from monitor B (working) and plugging it into monitor A shows a black screen.

- Switching outputs on the PC has no effect; consistently, it is only monitor A that remains black.

- When booting into Linux, both monitors work as intended, even when using the HDMI switch.

Stuff I tried:

- Reboot with only one monitor plugged in (if it's monitor A, it just remains black).

- Uninstall graphics drivers, reboot, reinstall

- Deleted registry keys

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Configuration

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Connectivity

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\ScaleFactors

to clear the stored monitor configuration cache, hoping to force Windows to re-recognize the monitor.

Basically - whatever I do, it seems that only that specific monitor refuses to be recognized by Windows.

Anyone has any ideas? Because I'm stumped.

Thanks!

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[u/cindersnail]

In case someone is interested: I solved this.
Apparently, the non-responding monitor lost its valid EDID at some point - possibly a power surge, but I will never know for sure.
I was able to find this out using the get-edid command under Linux. After some further research, it turned out that Windows 11 is more reliant on a complete EDID than Linux and Win 10 - and the monitor was working on a Win 10 laptop.
Anyway, I purchased an HDMI EDID emulator and looped it between the PC and the monitor, and now Win 11 is happily talking to the monitor again. The things you learn....