I had a 3770K @4.2ghz before I got the CPU I have now and there is no difference at all with the 1080Ti in 4K. I thought my CPU being so old might be holding my GPU back a little at least... Nope. You might get a small difference at 1440p but still I don't think it would be much. Certainly not enough to justify spending several hundred dollars.
I would recommend you just not upgrade. How fast is your ram? Can you OC your CPU any higher? Are the temps the issue or is it just unstable?
You can get a delid kit for like $10 on ebay now. As far as coolers, the 212 is the best cooler for the price and the Nuctua is the best cooler period short of custom water cooling.
DDR3 ram is also way cheaper than DDR4. What ram speed are you running now? get some 2133mhz ram if you haven't already.
Assuming you could overclock the CPU you have now more than you are now, just do that... and even if you can't you really don't need to upgrade. Unless you got those parts for dirt cheap, I would return them.
i7 7700kK @4.2ghz
16GB DDR4 3200mhz
GeForce 1080 Ti
Last edited by UltraMega; 02-15-2019 at 12:53 AM.