The Core i5 6600K is a great chip, but we did find some scenarios where an i7 would improve performance. Crysis 3 on very high settings (shadows dropped to high) could still stutter below 60fps in the jungle areas, or when heavy alpha and intense physics were deployed. Even with the i5 at 4.0GHz, the vintage 2013 title still causes issues for modern hardware. We've played this game a lot, and even older generation i7s hand in smoother performance on the very high preset. We also noted that the village stage in Rise of the Tomb Raider could max out the i5, causing stutter (a touch reduced in DX12), while galloping through Novigrad City could also tap out the i5 to its limits (though the 60fps lock remained intact).
Helping to prolong the life of PCs past, present and future is the fact that current - and indeed, future - consoles are based on relatively weak AMD CPU cores designed primarily for mobile applications. PlayStation Neo features the exact same CPU set-up, albeit with a 31 per cent clock-speed increase. We feel fairly confident that an i5 6600K can keep up for a good few years yet. On top of that, the Z170 board should be compatible with the future Intel Kaby Lake CPUs, plus you can upgrade from an i5 to an i7 for further gaming performance.