3900x + 4080s vs 9800x3d + 4080s ?!

Hey there guys, it seem like I got quite a bit of luck and a friend of mine is going to sell me his 4080 super for just 500 Euros.
So now I'm wondering if I should also upgrade my old Ryzen 9 3900x + 32 Gb of 3200mhz ddr4 ram.
I'd be getting the Ryzen 7 9800x3d + 32 Gb of 6000mhz ddr 5 ram.

I'm wondering if the 4080s + 9800xd + ddr5 would result in a significant (20+ percent) FPS increase vs the 4080s + 3900x + ddr4 build in games like:

Cyberpunk 2077
Witcher 3

I plan on gaming at 4k with all the bells and whistles like RT etc.

Thanks a lot for the input guys :)