After @wendell's great windows emulation video and write up, I'm looking into a new build to accommodate such a configuration.
I've been shopping for graphics cards and browsing this post regarding hardware mods to change device IDs. The following possibilities seem the best:
Gtx 690, with it half modded to be a k5000 or grid k2. -- Would it be possible to only pass one gpu to the vm?
Mod the 680 I already have to a k5000 or k2, and add a second card.
Get a pair of r9 380xs.
I'm really looking for gpu and cpu performance for both platforms on a single machine. So a dual socket 2011 with something like a pair of e5-2643 v2s(6-cores @3.5Ghz) and 32gb ram is what I'm looking at. Considering the easier route to pass an amd gpu to a vm, and the benefits of having a "k5000", gpu wise I am just looking for a configuration that could push through encoding and 4k gaming on mediumish settings. The more convoluted and sketchy the better.
Go R9, its so much easier to set-up with a a pair of AMD cards. Also you do not need a dual CPU build, 1 CPU will do, get an 8 core, allow 4 for host 4 for guest. For RAM allow guest 16 and other 16 for host. You will be fine there but no need for dual socket just go for more cores also 1 Physical Core does not exactly mean 1 vCPU core, you can allocate multiple cores to 1 physical CPU core as long as you don't peg it 100% all the time.
I used to run a passthrough with the nVidia 680 modded, I had two of them in my old Intel gaming rig, and it definitely worked. It was a hell of a job to get it working though, but a lot has changed in the last 4-5 years. From my experience though, I can definitely confirm that it's a hell of a lot easier to get things working on an AMD system. I mainly use AMD because of the trouble free virtualization, even though lately Intel seems to have caught up a little, there is still the matter of Intel not succeeding in producing any functional Beignet, and Intel not being able to produce proper power management modules until about a year after the hardware comes out. I've always been a great fan of the Intel Atom platform, because it's awesome how little power it requires for a pretty robust platform if used correctly, but Intel has pretty much kept early adopters standing in the cold for about a year, and it's still not entirely complete. AMD hardware might be older, but it's entirely supporting all virtualization functionality on almost all AMD and AMD-hardware-equipped OEM products across the board, for often obscenely low prices.