Samsung M321R8GA0BB0-CQK

First-generation DDR5 server platforms (Sapphire Rapids, Genoa) standardized on 4800MT/s as the JEDEC baseline before later refreshes pushed to 5600 and 6400MT/s; if your platform is a first-gen DDR5 server or you just want the safest, most universally-supported speed bin, this is the speed you're targeting regardless of brand.

This module pairs full-chip ECC (72-bit wide, 8 check bits per 64 data bits) with Registered (buffered) command/address signaling: an on-DIMM Registering Clock Driver (RCD) re-times CS/CA/CLK before they reach the DRAM dies, and an on-DIMM PMIC5000-series regulator converts the module's 12V/5V input down to the 1.1V DRAM rail locally rather than relying on the motherboard VRM, both standard JEDEC DDR5 RDIMM requirements. A JEDEC SPD5118 hub IC carries the SPD data plus an integrated temperature sensor (TS) the platform/BMC can poll for thermal decisions, a meaningful reliability feature on always-on workstation and server systems. The 2Rx4 (dual-rank, x4) layout splits the 64GB into two independently addressable ranks of x4 DRAM dies, giving the memory controller more open pages to interleave against than a single-rank module at a small rank-switching latency cost.

This module is JEDEC-standard DDR5-4800 CL40, the baseline speed bin first-generation DDR5 workstation and server platforms were validated against. AMD's Threadripper PRO 7000WX-series (Storm Peak, WRX90 chipset) officially supports 8-channel DDR5 ECC RDIMM up to DDR5-5200, so this 4800MT/s module runs at its own native JEDEC speed with headroom to spare, making it a safe, board-QVL-friendly capacity pick. On the server side it matches the DDR5-4800 baseline Intel's 4th Gen Xeon Scalable (Sapphire Rapids) and AMD's EPYC 9004-series (Genoa) launched with. Always confirm your specific motherboard's QVL before buying, since RDIMM support is validated per-model rather than universally across a chipset.

Within this catalog's ECC RDIMM lineup, this 64GB DDR5-4800 module sits between SK hynix's HMCG94AGBRA177N (64GB DDR5-5600 ECC RDIMM) and Micron/Crucial's MTC40F2047S1RC56BB1R (128GB DDR5-5600 ECC RDIMM, 3DS): same 64GB capacity as the SK hynix part but a lower, more universally-supported JEDEC speed bin, and a quarter the capacity of the Micron 3DS module at a meaningfully lower cost per DIMM. Against Samsung's own M321R4GA3BB6-CQK (32GB DDR5-4800 ECC RDIMM) already in this catalog, this part doubles capacity per slot at identical speed and rank behavior, the right call when you're maxing out DIMM slots rather than channel count. Against Kingston's Server Premier KSM64R52BD4-32HA (32GB DDR5-6400 RDIMM), Kingston clocks meaningfully higher but at half the capacity, so the choice comes down to whether your workload is bandwidth-bound or capacity-bound.