Saya Barak sounds for mem that your 6000mhz setting isn't stable.
so the ram calculate wrong values and crash the system.
check with karhu the system stability with 6000mhz. i'm sure thats not a bug of f20a, i believe that the clock is to high or your latency to less.

the performance of f15d is still the same like with f15c (i imported the previous pbo setting from f15c) (b550 aorus pro)
i see no changes. if somebody found something, please let us know.