ASROCK B550M/ac Manual Del Usuario página 28

2.3 Installing Memory Modules (DIMM)
This motherboard provides four 288-pin DDR4 (Double Data Rate 4) DIMM slots,
and supports Dual Channel Memory Technology.
1. For dual channel configuration, you always need to install identical (the same
brand, speed, size and chip-type) DDR4 DIMM pairs.
2. It is unable to activate Dual Channel Memory Technology with only one or three
memory module installed.
3. It is not allowed to install a DDR, DDR2 or DDR3 memory module into a DDR4
slot; otherwise, this motherboard and DIMM may be damaged.
4. We suggest that you install the memory modules on DDR4_A2 and DDR4_B2 first
for better DRAM compatibility on 2 DIMMs configuration.
AMD non-XMP Memory Frequency Support
Ryzen Series CPUs (Matisse):
UDIMM Memory Slot
A1 A2
- SR
- DR
- SR
- DR
SR SR
SR/DR DR
SR/DR SR/DR
24
Frequency
(Mhz)
B1 B2
- - 3200
- - 3200
- SR 3200
- DR 3200
SR SR 2933
SR/DR DR 2667
SR/DR SR/DR 2667