[SOLVED] Dummy DP and CRU resolutions not playing nice - windows10 AMD RX 6800

I bought some POS dummy DP port and am failing miserably at trying to set my monitors native resolution through CRU.
Native Monitor Resolution [email protected]
Current running resolution [email protected]

I have tried a few things, and most of the time the graphics driver crashes and windows restarts.


  1. set the timings with automatic(PC) and automatic(HDTV)
  2. set the timings manually derived from the link at (tomverbeure github io / video_timings_calculator)
  3. plug my monitor in and copy the resolution profile to the dummy plug
  4. remove all resolutions and set the one specific resolution i want

When trying to set the resolution in the AMD driver Custom Resolution page I get the message
“the custom resolution settings are not compatible with this display. reconfigure your settings and try again”

I’m at a loss as to where the issue is. I suspect the dummy DP plug does not support fast enough pixel clock, but i’m not sure how to check that.
A side note, there are resolutions showing in windows that are not specified on the dummy plug, I cannot work out where they are coming from.

AMD driver version is: 21.4.1

Moved to Windows - Level1Techs Forums, not an issue with Looking Glass

Thanks, sorry for the incorrect forum.
I’m not sure if it’s relevant that i’m running looking-glass to connect to the windows vm.

It’s a custom resolution, which is windows/driver specific, doesn’t matter that it’s a VM, or using LG, in both cases it’s still the same as using bare metal for this issue.

Yes, of course.

What I’m asking for is some assistance or guidance to determine the correct way to setup the custom resolution. Or determine if the plug I have is not adequate, due to pixel clock limitations or something else.

Closing a loop here, my windows machine died after 21H1 update so I had to start again, when installing a fresh OS I no longer have any issues with the dummy DP plug and can run full FPS and full UPS