I recently updated to Unraid 6.7 Stable and now I'm joining the group of being unable passthrough an Nvidia GPU to a Windows 10 vm.
ASUS x370-F Gaming
AMD Ryzen 7 1700
BIOS 4801 most up to date BIOS for this motherboard - like others confirmed, ASUS disabled reverting driver and like others have posted - downgrading BIOS is not the long term fix.
EVGA GTX 1080 Ti SC Black edition, with most recent ROM file from techpowerup.
Unfortunately the last time I booted the vm was January of 2019 on BIOS 4207 and was able to use GPU passthrough with no issues.
I'm am now receiving the same error - vfio: Unable to power on device, stuck in D3, then Unraid crashes after attempting to reboot.
I can switch to VNC and run the Windows 10 vm with no issues.
I did revert Unraid to the prior version, 6.7 rc6 but received the same errors. At this point I wished ASUS, and other MFGs, allowed downgrading the BIOS...
Will be following this topic.