Fritzo
Lifer
My current main rig is a 6600k/GTX-7700 upgraded from an FX-8350/GTX-6800 based system. Frankly under most circumstances the performance difference is not noticeable in anything other then benchmarks. I doubt seriously I would do it over again.
For new builds Kaby Lake is no question the way to go but for most folks an upgrade from any decent CPU is a waste of money IMO.
Triple monitors are the thing in gaming now, so you'd probably notice a difference there (with a paired memory card of course)