Since you ordered the i7-7700K already I debated whether to write THIS comment...
I would have recommended an 8th gen (coffee lake) CPU instead. Possibly the i5-8400 or i5-8600K. If you can return and/or change the order maybe you can ask about that and discuss the pros/cons.
Not sure if the i7-7700K was on sale, but unless the motherboard + CPU cost (comparing similar quality motherboards) of the i7-7700K vs similar coffee lake is cheaper I'd go 8th gen.
*In fact, the i5-8600K is a 6C/6T (six cores without hyperthreading) CPU whereas the i7-7700K is a 4C/8T CPU so basically the i5-8600K has six fast cores with no hyperthreading per core (which for six-core CPU's is hard to utilize in gaming and at BEST may add 30% performance for very hyperthreaded tasks like Handbrake).
The i5-8600K and i7-7700K will be nearly IDENTICAL performance for most games though, but for multi-tasking, a few current select games, and FUTURE PROOFING the i7-8600K is a better choice.
The i5-8400 is more complicated as it has a max 4GHz frequency per core which may or may not be sustainable even if you carefully tweak the BIOS. It is only $200USD last I checked though and is a 6C/6T CPU (six cores, no hyperthreading).
The i5-8400 in most games either matches or falls BEHIND the i7-7700K in performance though not when considering VALUE if the i7-7700K costs more.
So again, budget aside I'd probably go with the i5-8600K (even the i7-8700 and tweak to run all cores at 4.6GHz) depending on your total BUDGET.