Stefan Mileschin

Samsung this week demonstrated its first 256 GB memory module for upcoming servers. The new Registered DIMM (RDIMM) is based on Samsung’s 16 Gb DDR4 memory devices introduced earlier this year and takes advantage of the company’s 3DS (three-dimensional stacking) packaging. The new module will offer higher performance and lower power consumption than two 128 GB LRDIMMs used today.

Samsung’s 256 GB DDR4 Registered DIMM with ECC carries 36 memory packages featuring 8 GB (64 Gbit) of capacity each, along with IDT’s 4RCD0229K register chip (to buffer address and command signals and increase the number of ranks supported by a memory channel). The packages are based on four single-die 16 Gb components that are interconnected using through-silicon vias (TSVs). Architecturally, the 256 GB module is octal ranked as it features two physical ranks and four logical ranks.

On a bit more of a technical note here, it's very interesting to point out that these new DIMMs are Registered DIMMs (RDIMMs) and not Load-Reduced DIMMs (LRDIMMs). Normally, LRDIMMs are required for high capacity configurations, with these style DIMMs relying on additional buffering that hurts power consumption and latency versus RDIMMs. Instead, because the latest server platforms (AMD EPYC, Intel Xeon Scalable, etc.) have shifted their memory requirements to natively support support octal-ranked modules in both slots - at the cost of being limited to two slots per channel in total - LRDIMMs are not necessary to maximize the memory capacities of these new servers. As a result, simpler RDIMMs can be used instead. I suspect this is a big reason why Samsung decided to go with a 256 GB RDIMMs, as they are a natural pairing with the latest servers.

https://www.anandtech.com/show/13500...o-servers-soon