ASrock have created a "HUDIMM", which is basically a half bandwidth DDR5 DIMM. Basically half the number of chips per DIMM. So kinda a modern day 386SX with its 16 bit bus. Presumably hoping you'll be able get fewer, higher capacity DRAM dice for a competitive price versus a normal DIMM.
On modern systems (all 64 bit AMD, and Intel Core "i" onwards, so quite old now) the memory controller is integrated into the CPU, so what the CPU supports is what you get, and the latest CPUs are DDR5 only. Intel did have a transitional phase of CPUs that can do both DDR4 or 5 depending on motherboard, but AMD it's AM4 = DDR4, AM5 = DDR5.
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ASrock have created a "HUDIMM", which is basically a half bandwidth DDR5 DIMM. Basically half the number of chips per DIMM. So kinda a modern day 386SX with its 16 bit bus. Presumably hoping you'll be able get fewer, higher capacity DRAM dice for a competitive price versus a normal DIMM.
On modern systems (all 64 bit AMD, and Intel Core "i" onwards, so quite old now) the memory controller is integrated into the CPU, so what the CPU supports is what you get, and the latest CPUs are DDR5 only. Intel did have a transitional phase of CPUs that can do both DDR4 or 5 depending on motherboard, but AMD it's AM4 = DDR4, AM5 = DDR5.