Thanks for the reply. I understand what you're saying and those minimum frames is very important. I don't know if I will be doing it though. I'd need a new Mobo, the CPU and RAM and I just ordered another 16GB of DDR 4 RAM
haha. The CPU is pretty expensive though at over $600. I wonder how a 12700k fairs. One other thing to consider is that at 4K these CPUs all seem to give about the same performance. I'm not sure about the minimum FPS as I don't remember if I saw that in the benchmark I watched but the Average FPS was all pretty much equal between all the CPUs at 4k. Guess I will wait and see for now.
You are on the edge of whether you should upgrade or not. If you were building from scratch I would not recommended a 6 core chip to go with a 3080ti, but you already have the 8700K so it doesn't cost you anything. If you did upgrade I would stick with DDR4 though, I haven't seen anything that justifies the expense in DDR5 for games. The 12700K is as good as the 12900K, the latter is up to 19% faster overall because it has slightly higher clocks, a slightly bigger cache and 4 more efficiency cores. In games though they are basically the same as they share the same number of P cores but with the tiniest clock differences (100mhz all core boost). Here in the UK it's 52% more money for the 12900K for no gaming advantage so I'd buy the i7 if I was building now. I would expect either to last a very long time.
Even at 4k there will be differences between the CPU's. What a new chip will give you, particularly at that resolution is better frames due to consistent frame times not necessarily more frames so motion for example will be smoother. How perceivable that will be to you on a day to day basis I'm not sure, it will largely depend on the game.
Cyberpunk for example will be noticeably better in the most demanding scenes on a 12th gen chip if you run with max ray tracing and stuff like that even at 60hz, though that is a fairly rare exception.
I am confident you are leaving some performance on the table, I think you will notice a difference. What I'm not sure about is how consistently you would notice any improvement, and when you do will your reaction be 'oh that's nice' or 'omg this is amazing'. I would expect the former to be more common than the latter.
Upgrades are more impressive when there's something that you don't like about your current system. If your generally very happy with the 8700K's performance and this is more speculative about whether or not it's worth it given you have a new graphics card. Then maybe you should wait until you move to a game where you feel I could use a little bit more here.