HA! I finally managed to get the virtualization and device passthrough working for about 3 weeks. My approch is very similar to Wendels Guide for IOMMU on Ubuntu 17.04 but less refined 
(Ubuntu 17.04 -- VFIO PCIe Passthrough & Kernel Update (4.14-rc1))
I can now confirm that the ASUS ROG Crosshair 6 Hero works for IOMMU. But robust results require of course BIOS version at least 15.01!
Now it performes pretty neat
Mit freundlichen Grüßen
Marfy
@ Sanfordvdev,
I testet Unigine Valley and Superposition on Window 10. On native Machine I messured around 54 FPS avg, virtulized with gpu passthrough round 49 FPS almost 50 FPS avg in Valley. And 19.3 FPS avg vs. 18.5 FPS avg in Super Position.
Please take a look on my post in the Ubuntu GPU Passthrough HowTo from Wendel here:
I played ARK also, nearly same Performance - location depended dangeling between 35 and 50 FPS in slidly below High Settings. BTW I used an Sapphire Pulse Radeon RX 560 4GB VRAM overclocked to 1440 Mhz GPU and 2 GHz VRAM.
PS: I’m limited to do only 3 Replys here 