I have a 13900k and there really few and far between workloads that can use the sustained all 40 threads to its maximum. I do high performance computing and encoding besides gaming. I get 100% usage with some very specific R code, Python only goes above 1 core for very short durations and handbrake uses ~60% of the cpu for software x265. Also you’ll need faster ram to get the most of it and cooling it is a harder as well. I’d go with the 14700k, save the difference and place it towards the gpu

If you have a modern os I think you don’t need to format, but on the long run, it’s probably better to do it.