New Enterprise Memory To Use Less Power

Thursday, 10 December 2009

By Pallab Chatterjee
With the release of the EnergyStar rating for servers, there have been a number of approaches to meet the requirements for increasing density and performance. Standards communities such as JEDEC and the 40G/100G networking associations are currently finalizing adoption of the Isolation Memory Buffer (iMB) technology for new high-performance memories.

The use of this technology creates a new class of memory module called the LRDIMM, or load-reduced dual inline memory module. This technology was developed by Inphi, a 10-year-old high-speed analog semiconductor company from Sunnyvale, Calif.

The key issue for modern data centers is how to address growing performance needs while decreasing power budgets. LRDIMM technology is supported by a custom logic controller chip that handles buffering through a standard load interface. The key is a high signal integrity-based memory buffer that has a fixed load to the bus independent of the memory depth behind it. This allows configurations that would be using one bank of memory to support up to eight banks of memory in the same speed and bus power. For compatibility and optimization with multicore CPUs, the iMB interface includes task-based duty-cycle reduction and deep memory idle states.

The iMB parts use dynamic termination of the memory banks to manage power for DDR3 operation at 800, 1066, 1333 bus speeds at both 1.35v and 1.5v operation. These features are also supported through the new JEDEC 1600 spec and will be scalable to DDR4 3200 applications.

The LRDIMMs will be built in Q1 by Hynix, Samsung, Micron, Naya and others using the Inphi chips. The products are currently only for enterprise-class EnergyStar applications as the Inphi chip that is being used costs about $25 in quantities of 100,000. The advantage of the technology is the power reduction and density/performance improvement while still maintaining the 10-12 BER and supporting a single chip/single cycle load for both command and address signa

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