MRDIMM

MRDIMM, short for multiplexed rank dual in-line memory module, is a DDR5 server module that runs two ranks at once and merges their data through a buffer chip. Operating both ranks together lets it feed the CPU 128 bytes, twice the 64 bytes of a standard DDR5 module. That raises the data rate the host sees. It is also known as MCRDIMM, and the processor must support it.

The Intel Xeon 6980P runs standard DDR5 at 6,400 MT/s and MRDIMM at 8,800 MT/s across 12 memory channels. AMD lists the 16-channel EPYC 9656 at up to 8,000 MT/s with registered DIMMs (RDIMMs) and 12,800 MT/s with MRDIMMs. That lifts peak bandwidth from 1,024 GB/s to 1,638 GB/s per socket. Lenovo summarizes the JEDEC roadmap as 8,800 MT/s for first-generation MRDIMM and 12,800 MT/s for the second generation. Tall form factor (TFF) MRDIMMs add DRAM chips for capacity but fit only servers 2U or taller.

Specify MRDIMM for bandwidth-bound work only on a CPU whose spec sheet lists it, such as the Xeon 6980P or EPYC 9656. Everywhere else, use standard RDIMM.

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Last verified October 7, 2026.