Large Modules for Large Servers

Micron this week introduced that it had begun sampling of its 256 GB multiplexer mixed (MCR) DIMMs, the corporate’s highest-capacity reminiscence modules to this point. These brand-new DDR5-based MCRDIMMs are aimed toward next-generation servers, significantly these powered by Intel’s Xeon Scalable ‘Granite Rapids’ processors which can be set to help 12 or 24 reminiscence slots per socket. Utilization of those modules can allow datacenter machines with 3 TB or 6 TB of reminiscence, with the mixed ranks permitting for impact knowledge charges of DDR5-8800.

“We additionally began sampling our 256 GB MCRDIMM module, which additional enhances efficiency and will increase DRAM content material per server,” said Sanjay Mehrotra, chief government of Micron, in ready remarks for the corporate’s earnings name this week.

Along with asserting sampling of those modules, Micron additionally demonstrated them at NVIDIA’s GTC convention, the place server distributors and clients alike are abuzz at constructing new servers for the following era of AI accelerators. Our colleagues from Tom’s Hardware have managed to seize a few photos of Micron’s 256 GB DDR5-8800 MCR DIMMs.

Picture Credit score: Tom’s Hardware

Apparently, Micron’s 256 GB DDR5-8800 MCRDIMMs are available two variants: a taller module with 80 DRAM chips distributed on each side, and a standard-height module utilizing 2Hi stacked packages. Each are based mostly on monolithic 32 Gb DDR5 ICs and are engineered to cater to totally different server configurations with the standard-height MCRDIMM adressing 1U servers.The taller model consumes about 20W of energy, which is consistent with expectations as a 128 GB DDR5-8000 RDIMM consumes round 10W in DDR5-4800 mode. I do not know about energy consumption of the model that makes use of 2Hi packages, although anticipate it to be a bit bit hotter and tougher to chill down.

Picture Credit score: Tom’s Hardware

Multiplexer Mixed Ranks (MCR) DIMMs are dual-rank reminiscence modules that includes a specialised buffer that permits each ranks to function concurrently. This buffer permits the 2 bodily ranks to function as if they had been separate modules working in parallel, which permits for concurrent retrieval of 128 bytes of knowledge from each ranks per clock cycle (in comparison with 64 bytes per cycle with regards to common reminiscence modules), successfully doubling efficiency of a single module. After all, for the reason that modules retains bodily interface of ordinary DDR5 modules (i.e., 72-bits), the buffer works with host at a really excessive knowledge switch charge to switch that fetched knowledge to the host CPU. These speeds exceed the usual DDR5 specs, reaching 8800 MT/s on this case.

Whereas MCR DIMMs make reminiscence modules barely extra advanced than common RDIMMs, they improve efficiency and capability of reminiscence subsystem with out rising the variety of reminiscence modules concerned, which makes it simpler to construct server motherboards. These modules are poised to play a vital position in enabling the following era of servers to deal with more and more demanding purposes, significantly within the AI subject.

Sources: Tom’s Hardware, Micron