up, up, down, down, left, right, left, right, B, A ?
2 CPUs + 8 DIMMs on my SMCI X9DRH would be:
P1-DIMMA1 P1-DIMMB1 P1-DIMMC1 P1-DIMMD1 P2-DIMME1 P2-DIMMF1 P2-DIMMG1 P2-DIMMH1;
where PX-DIMMY1 & PX-DIMMY2, or Y0 & Y1, relating back to your board;
so A0 B0 C0 D0 E0 F0 G0 H0