The I7-7700K is a 91w tdp processor.
More, of course if overclocked.
How well you can overclock is determined by the quality of your chip and the vcore required for the overclock.
1.4v is generally the top recommended vcore.
Not all chips will do 5.0.
As of 6/9/17
What percent can get an overclock at a somewhat sane 1.4v Vcore.
I7-7700K
4.9 83%
5.0 62%
5.1 29%
5.2 6%
If you want a guarantee 5.0 oc, spend a bit more for a well binned sample.
Silicon lottery sells them, plus a delidding service.
https://siliconlottery.com/collections/lga-1151
The cooler you need is more modest than you may think.
The noctua site has some good info on this.
Here is a link:
http://noctua.at/en/products/cpu-cooler-retail/tdpguide
The NH-U14s would be one example of an appropriate cooler.
As always, you need a case that has sufficient fresh air intake capability for the cooler to do it's job.
Two 120mm front intakes or better is sufficient.