Per Buildzoid, Asus having the memory traces for channel A visible on the board is the reason for the low RAM clocks. Seems dumb to have an 8+ layer PCB and to do that
Probably part of it, but a pretty unsatisfactory explanation for bad mem OC performance. Plenty of other cheaper 6-8 layer AM4 boards of all sizes don't have shielded memory planes, and do better. Lazy Asus is just milking it on AM4 with mediocre designs, and they know full well.
They don't have any motivation to improve their memory topology design, look at this board and the "new" Strix-XE. They know that 99% users don't venture past Fabric limits, they know that most users aren't running APUs, they know that AGESA makes for a wild ride for memory OC, they know that there's no pressure from DDR5, they know that AM4 is almost dead.
And honestly, look at this board. It's the Formula's big bro. Feature-packed, but if you don't need those niche features, it's just a poser board (muh VRM) with no OC credentials whatsoever. I honestly hope the Impact is either replaced or supplemented by a proper Apex for AM5.
The Z690-esque VRM on it is just the cherry on top. I get similar (if not better) torture thermals with 6 less phases on the B550 Unify-X, which is already laughably overkill.