The only real difference between the 4790k and any of the v3 Xeons is clock speed. And with the IPS of the i-series chips, the clock speed isn't a big factor. The i5-4690k at 3.5Ghz benches almost identical to the faster 4790k, so there is really not much, if any, performance loss by using the Xeon v3 chips, which will game just as well, but likely perform better in modern applications and threaded game titles, like I said before.
The i7-4790k is unlikely to have any gaming advantage over the Xeon or i5, except in game titles that are heavily CPU dependent, and those are few and far between. Most games are GPU bound and so long as you have something like an i3-4360 or higher, you can game on with pretty much any GPU you want. Any...