ASROCK B660 Pro RS Manual Del Usuario página 18

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.
Dual Channel Memory Configuration
Priority
1
2
The DIMM only fits in one correct orientation. It will cause permanent damage to
the motherboard and the DIMM if you force the DIMM into the slot at incorrect
orientation.
14
DDR4_A1 DDR4_A2
Populated
Populated Populated
DDR4_B1 DDR4_B2
Populated
Populated Populated