The Key Component To Increasing Memory: FBDIMM

FBDIMM—or DDR2 fully buffered dual in-line memory module—differs from DDR2 due to the addition of an Advanced Memory Buffer (AMB), said Craig Stice, senior marketing operations manager for DDR2 at Micron Technology, a Boise, Idaho-based mem-ory supplier.

With the AMB, FBDIMM memory modules communicate directly with each other in order to increase performance over DDR2 memory, Stice said. “This takes standard server memory modules into the years to come,” he said.

Tom Trill, director for DRAM marketing at San Jose, Calif.-based Samsung Semiconductor, which is also preparing to bring FBDIMM memory to market, said that FBDIMM with its high-performance AMB represents a radical change in memory technology.

However, said Trill, this increased performance comes at a cost: AMB on a memory module doubles the power consumption compared to DDR2. That power consumption can be significant in data centers, especially the estimated 14 percent of data centers that are already using server blades, Trill said. “Memory can account for 25 [percent] to 40 percent of total power consumed by a server, based on platform design,” he said.

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While both Micron and Samsung are expected to come to market with FBDIMM modules ranging from 512 Mbytes to 4 Gbytes, Trill expects the initial “sweet spot” to be in the 2-Gbyte capacities.

At launch, FBDIMM memory will run at 553MHz, with 667MHz versions expected to ship a couple months later, Stice said.

Unlike the Intel processors, Advanced Micro Devices’ Opterons have an embedded memory controller to cut power use and decrease memory bottlenecks, and so have been limited to working with DDR1 memory, said Andy Kretzer, director of sales and marketing at Bold Data Technology, a Fremont, Calif.-based system builder.

However, AMD, Sunnyvale, Calif., is moving to support DDR2 with the introduction of 667MHz frequency modules. “AMD thinks it’s a huge benefit for its processors to have embedded memory controllers, even though it boxes them into one type of memory,” Kretzer said.