ASUS ROG MAXIMUS Z790 APEX ENCORE LGA 1700 ...
On booting the PC, I discovered that both B1 and B2 RAM slots were not working. PC doesn't boot if I put RAM on either B1 or B2 slot.
Best RAM for gaming 2025 - PCGamesN
hmmm, turns out the ram was in the wrong slot the whole time. It was in A1/B1, should have been in A2/B2. That allowed me apply the DOCP (amd xmp) profile in bios.
The right way to put RAM in your PC's memory sockets | PCWorld
With one RAM stick, you can install it in any of the slots but preferably right next to the processor channel. With two sticks, install it in A1-B1 or A2-B2 format.