From what I have read the 7700k is known for running hot. They say that Intel messed up on there thermal on the core that's why people delid 7700k commonly. Most do it to oc more I did it to cool my system down. But yes the new Intel with more cores, higher frequency, more power = hot cpu and might all need water and/or a delid but that's just an assumption
The i7-8700k is for sale, but from what I heard the coffee lake CPU runs cooler than the i7-7700k, not only during overclock, but also at stock speeds, even with two more cores, and an equally high boost on at least 2 cores, and single core boost doesn't generate much heat, but thats still going to match the clock speeds of the i7-7700k.
Well that's good to know for newly buyers. The 770k, tho a great cpu is hot. My case is kinda the culprit too maybe idk but with a 360mm cooler should... Should be cooler