Hey,
I am in a similar situation. I have 2 unRAID machines, and I'm looking to get VM's up on them soon my self, but I'm having some difficulty getting video output on the one I'm working at at work with more server style hardware. I'll be playing with my home set up this weekend to see if I can make any headway there with different hardware.
I'm in a similar position as m1a8x2 here as I have tried almost everything I've see on the forums here or in Spaceinvader One's videos on youtube.
My hardware is: Mobo: TYAN - S5396
CPUs Dual Xeon 3.0ghz
GFX GeForce GTX 760 ( I do have other options and cards I can use)
16gb ECC RAM PC2-5300f
The only issue I KNOW I have with my hardware is that it beeps at me if I have a gfx card in the first PCIe slot when I try to boot it. But it seems just fine in the other PCIe slot until I turn on the VM.
Now I did run in to issues getting the IOMMU enabled on my mobo at the beginning of my adventure at work here, but I updated the BIOS and turning on the intel vt-d didnt disable the nic's on my board anymore haha.
Here is one of my VM's XML I did try an unedited gpu bios, and an edited one.
Here is my IOMMU groups.
And sorry m1a8x2 I don't mean to hijack your thread, I'm just in a very similar place.
I wont be back at work till monday. But I'm fairly stuck. I have a few different VM's loaded up and ready to go, and nothing will pass through the GPU. Tried SeaBIOS and ovmf, and so far just hitting a wall.
Thanks for any help!