Decided to go from a 2080 to a 7900xt for my VM. I couldnt get it to work, despite every resource telling me how easy it should be. So I nuked the VM and started from scratch just to have the same problem.

VNC works great, but the only thing displaying on my monitors is a black screen once I pass through, then the monitor times out and turns off.

I thought maybe it needed a graphics RAM bios (even though I never had to do that with any of the 3 Nvidia cards Ive use in this server), but even SpaceInvader's old instructions on how to pull the vbios isnt working. His user script is saying:

Um.... somethings gone wrong and I couldn't dump the vbios for some reason
Sometimes when this happens all we need to do to fix this is 'stub' or 'bind to the vfio' the gpu and reboot the server

This can be done in Unraid 6.8.3 with the use of the vfio config plugin or if you are on Unraid 6.9 or above it can be done
directly from the gui in Tools/System Devices .....So please do this and run the script again.

Which I did, and its still not working.

The vbios for this card (ASRock Phantom Gaming OC Radeon RX 7900 XT 20 GB) on techpowerup is unverified, but i tried it anyway and its not working either.

Could It be that Im not binding enough to VFIO at boot? Right now ive tried binding group 27 & 28, as well as 28-33, neither worked? What should be the correct combination ?

GPU worked great in my bare metal machine. Doubt very seriously its that.

Try not to passthrough the Audio if that works.

Edit: Or try not to add the sound card in the VM settings.

Edited September 22, 2025Sep 22 by PUNGGOKERS

I put the Nvidia card back into it; ran out of time to trouble shoot. Hopefully sometime this week I can give that a try. Thanks.
I also read of someone who had the same issue as me and fixed it by turning off resizable bar in the bios. Have you heard of that being a common issue on AMD cards?

Could be, it's easier to tell if you have diagnostics that we can review. But usually it's just a VM quirk.

Passing through just the video without the sound counterpart didn't work unfortunately. I did finally get it to work however by turning off SAM/Resizable bar which also turned off UEFI and turned on CSM. Which is not really a solution in my mind as SAM/resizable bar is pretty much essential for a lot of newer games these days. Also, the VM is just generally running like crap, lots of hiccups and even a few hard and total VM failures where its just black screens and turns the VM off. Ive been running the same VM setup for years with 0 issues on a 2080 and now I really regret "upgrading".

Anyone know how to get resizable bar running on AMD GPUS? Ive seen online that is doable, but all their solutions are either outdated and not longer applicable to my case, or they just are not working for me. Its an Asrock 7900 xt for reference.

I see that in your XML, your machine is Q35-9.2. Can you try changing that to i440fx? Sometimes, that fixes the problem.

Another thing is to type this in the terminal BEFORE and AFTER running the VM. Let me know what the terminal will show us. Make sure resizable bar is turned on.

dmesg | grep -i vfio

Edited October 1, 2025Oct 1 by PUNGGOKERS

Thanks @PUNGGOKERS for the help! I did however figure it out! Turns out the solution was fairly simple.
TLDR: The unverified vBios I got from TechPowerUp must not have been good but booting in CSM (resizable bar off) allowed me to actually finish SIOne's user script.

For anyone finding this later: These are the steps I did to fix my issue.

I reset my Bios to default,
Turned off Resizable Bar (this also forced CSM boot among other things)
Verified IOMMU was enabled and SVM was Enabled as well in the bios.
Booted, logged in etc and dumped the vBios per SIOne's script
VMS>Edit> Point the Graphic ROM Bios to the one that was just created (should be user>isos).
Verify that USB & PCI devices are passed through properly etc (standard stuff). Update VM, do NOT try to start it.
Go back to Bios and now re-enable resizable bar and UEFI.

Log in, start the VM
(This is the important bit I think I missed the other times) WAIT a long time! It took about 5 minutes for the screen to actually display but display it did!

Im guessing that the vBios is what made the difference for me. TechPowerUp apparently did not have a good copy of my bios and for some reason every other time I tried to dump my own it it would not work. I think I might have had something strange set up in my bios that was keeping Unraid from actually fully seeing/accessing my GPU. Once I dumped the vbios, everything went as advertised.

If you are reading this before you bought your GPU, I highly recommend that you just buy Nvidia, Ive had 4 different Nvidia GPUs in this same server/VM and they were all plug and play, no fuss whatsoever; resizable bar just worked.

Edited October 3, 2025Oct 3 by BoltActionBacon