New MCR DIMM Modules Are Doomed
We expect MRDIMMs to take over in HPC systems much sooner than many anticipated
It is time to write the obituary for an exciting new technology just before it really launches. The MCR DIMM, short for Multiplexer Combined Rank DIMM, is a higher bandwidth slotted memory solution that Intel has been touting for over a year and a half. Ultimately, we believe it will give way to another technology, and shockingly quickly.
As a quick refresher, the idea of MCR DIMM is to simultaneously operate two ranks of DRAM on a single module and deliver 128bytes to a CPU (64 bytes from each rank) roughly doubling the performance per DIMM.
The above explainer image from SK hynix shows how the MCR DIMM works at a high-level. An impact of the MCR DIMM is that one can get more bandwidth on a single DIMM device. With MCR DIMMs operating at 8800MT/s, Intel has a way to offer more bandwidth than the HBM2e equipped Intel Xeon Max processors using higher-capacity DIMMs in standard DIMM slots. MCR DIMMs were set to offer a lot more memory bandwidth per CPU on Intel’s upcoming Granite Rapids processors in Q3 2024 and x86 HPC customers have been excited about the prospect.
During the Intel Xeon 6 “Sierra Forest” launch in early June 2024, the company showed Granite Rapids or the Intel Xeon 6900 Series with P-Cores supporting MCR DIMMs at up to 8800 MT/s.
At FMS 2024, in early August, we saw a number vendors showing off MCR DIMM solutions that were said to support next-generation Intel CPUs.
Everything seemed vibrant for the MCR DIMM but it seems like the market has since changed and we think Intel is losing its focus on MCR DIMM support for Granite Rapids/ Xeon 6. Instead, other plans are afoot.