We have close to the same build and I haven't had any problems with my 7700K not being good enough feeding the 2080ti at 1440p. Is your 7700K delidded? I'm hoping I can get close to 5ghz with the nh-l12s and 120mm noctua fan installed as my 7700K does 5ghz stable at low vcore.
Yes it's delidded, but I only currently run the cpu at 4.8, no crazy clock just because I don't play heavy games. Heaviest game I play is bf1 and will get bf5 at some point. If this is the case and that's what you get, I should just put my budget towards better gpu & better cooling.