Intel DDR2 FB-DIMM Performance

FB-DIMMs are not compatible with current DDR2 setups, as they require a distinct memory controller. Intel has adopted this technology with their Blackford and Greencreek Chipsets, while AMD has yet to pledge any FB-DIMM capable components. We had anticipated that we could possibly see AMD's FB-DIMM adoption occur with their new Socket F, which is due out later this year, however, a reliable source has denounced such an implementation. The system used to perform our FB-DIMM benchmarks was based upon a pre-production model of the Tyan Tempest i5000XL S2692. The Tempest i5000XL is designed to be a server/workstation motherboard, and uses Intel's Greencreek MCH and ESB-2V. While this motherboard is not yet available through the retail channels, it boasts four 240-pin DDR2 FB-DIMM slots. The dual-core CPUs supported are dual LGA-771-based Xeon Dempsey and Woodcrest processors. For our purposes today, we used an Intel Xeon 5080. The Xeon 5080 is a dual-core Dempsey-based processor with 65nm manufacturing, and a clock frequency of 3.73GHz. There is 2MB of L2 cache per core with a 1066MHz FSB. Intel's Hyper-Threading is supported with the Xeon 5080, which brings the logical core count up to four.

With the Tempest workstation setup we have here today, each of the four FB-DIMM modules have their own memory channel, which should prove to provide a substantial bandwidth advantage over traditional dual channel memory. For comparison, we also ran the same set of tests with the Tyan Tiger i7520SD, which is based upon the Lindenhurst E7520 Chipset, and supports dual Xeon LV Sossaman processors. The memory supported by this ATX motherboard is Registered DDR2-400 in dual-channel mode. Up to 16GB is supported by the memory controller. The processors used for this testing were two Xeon LV (Sossamamn) parts clocked at 2.0GHz with 2MB of L2 cache per core.