Valve has a program to detect if your system can ran the valve index. Are you ready for Valve Index? on Steam
It says the R9 series (Fury-X in my case) is compatible but it's really not (not a single person has gotten it to work correctly with the Fury-x) when I asked steam support why it says it is but it's really not they blamed AMD's drivers:
From what I understand the Fury-x is a good 20% better (over all performance) then recommended GPU's.
So I'm wondering if AMD has said anything about making it compatible in the future?