I am running an i7-4770k
Windows 8 64bit
Nvidia 770 4GB
I can tell you without reservation that performance of the beta is pretty much flawlessly smooth no matter what on my rig at 1920x1080 at maximum game settings.
So whether it's my current cpu/mobo, windows 8, the 4GB video card or a combination thereof, the point is that it's running perfectly.
windows 7 atm cause a bit of a mess.