ASROCK B450 Pro4 Manual page 26

Ryzen Series CPUs (Raven Ridge):
UDIMM Memory Slot
A1 A2
- SR
- DR
- SR
- DR
SR SR
SR/DR DR
SR: Single rank DIMM, 1Rx4 or 1Rx8 on DIMM module label
DR: Dual rank DIMM, 2Rx4 or 2Rx8 on DIMM module label
24
Frequency
(Mhz)
B1 B2
- - 2933
- - 2667
- SR 2667
- DR 2400
SR SR 2133
SR/DR DR 1866