i7-7700k will run at 4.5Ghz on its own, that is it's target boost frequency. As long as temperature allows.
Memory shouldn't automatically run at 2666, it will default to 2133 unless you have instructed it to use the XMP profile.
You can force the CPU to run at 4.5Ghz all the time, just by changing the base multiplier, shouldn't need any extra voltage (you might even be able to get away with less). But even an h60 should be able to get you to 4.8Ghz or so with a mild overclock.
Most useful guide I have found:http://www.tweaktown.com/guides/7481/tweaktowns-ultimate-intel-skylake-overclocking-guide/index.html
Skylake and Kabylake are pretty much identical, so you can follow the voltage and temperature recommendations. Max frequency on Kabylake is a quite a bit higher, but at the expense of greater heat. They'll run fast, just don't expect them to stay cool doing it.