I feel like I'm being bothered by the same thing. I am currently able to successfully enter the win11 system, and the GPU can output images to the monitor normally. The driver can also be installed normally. Everything looks fine. But win11 cannot be shut down in any way. Once turned off, unraid will freeze and trigger the motherboard to power off and restart, and the sound of the power relay can be heard.
The platform I am using is 13500t+z790m+7800xt+ddr5 4800.
I tried most of the items in the motherboard settings, to no avail.
CSM is off, vtd vtx is on, sdiod is on, iommu is off (or on, no change)
After my observation, after clicking the virtual machine to shut down, the core assigned to win11 will be fully loaded, and qemu seen in the top command is the first. The memory is not released at this time. Then qemu can no longer see it and the memory is released. But the libvirtd process will load up single or dual cores, and then I can no longer connect to unraid.
Another strange thing is that after unraid crashes, The router's pppoe link will crash. until the system is restarted.