It looks like MVC has tested Occulus Rift on two Mac Pros and it succeeded in both cases:
nMP 6,1 with added GTX 1080 via eGPU
cMP 4,1/5,1 with added Titan-X and USB 3.0
Yeah, i don't trust his posts , he is a complete douche that will not help the community and explain how to get TB egpu working under Windows on the nMP, I have doubts about these results, and validity