I’d get 350w/400w. It might work fine with 300w as well, but the PSU utilization will be near max under load

probably not

I personally think you should get i3-13100f /s

Why are you buying a PC? what is your build? what is your budget?

Overall 14700k is very capable and might be comparable to 13900k in many (most?) cases.

But if you want more power, maybe you should get the new threadripper

But you also said you are flat on money, so which one is it? The fact that you could buy 4090 / can buy 14900k doesn’t mean you should

Before upgrading your CPU

1. What fps do you get?
2. What is your screen resolution? Refresh rate?
3. What is your game config? Which games?

Do you play CS 2 and getting only 400 fps instead of 600 on 1440p and it bothers you? Or do you play 4k games with RT on maxed out graphics but not fully utilizing your GPU?

13700f is fairly strong, and should be capable of handling relatively high frame rates, so your game configuration might have a lot to do with your bottleneck.

If you are tight on money DON’T upgrade your PC, especially if it’s just because of neglectable bottleneck.