I dragged the Rift setup into the Lab where the cMPs are. Hooked it up to a 4,1/5,1 with a 3.46 6-Core and a Titan-X.
To make sure it would work well, I also used an Inatek USB 3 card.
Setup was even easier than 6,1 nMP.
On the plus side, it ran perfectly. On the "minus" side, it kept remid=nding me that my hardware wasn't good enough. I think it meant the built in USB 2 or the Westmere CPU.
But it ran just fine.
The game Chronos was smooth and efficient, looked good and ran smoothly.
I may try with just the USB 2 and see what it does. But it is proven, there are Macs that can run VR. They just need a little help.