Two DRAM module manufacturers, Smart Modular Technologies Inc. and Kingston Technology Co., have separately introduced nonstandard, low-latency 2.2.2 PC2100 server DIMMs for streaming video and high-performance enterprise applications.
The JEDEC-standard PC2100 DIMM has standard CAS latency of 2.5, PRCD RAS-to-CAS delay of 3, and PRP precharge latency of 3 (18.104.22.168). However, the two companies' 2.2.2 DIMMs have data out of 30ns, compared with 41.25ns for the JEDEC module. This allows faster memory data speed up to 2.1Gbytes/s and allows the processor to operate at higher performance levels, according to Arthur Sainio, strategic marketing manager at Smart Modular, Fremont, Calif.
Although no industry standard exists for the 2.2.2 DIMM, both Smart Modular and Kingston said they test their modules to qualify them as meeting the new low-latency specification.
Mark Tekunoff, senior technology manager at Kingston, Fountain Valley, Calif., said that white-box makers are a target market for the low-latency modules because they want to differentiate their systems from Tier 1 competitors.
Both companies stressed that the low-latency module allows servers to read and write to memory in fewer clock cycles than the standard-latency DIMM.
Sainio said the 2.2.2 low-latency modules use DDR266 SDRAMs, with Infineon Technologies A.G. currently the only supplier. However, Samsung Semiconductor Inc., a San Jose-based subsidiary of the Korean chipmaker, said it would supply the DDR266 parts if there was sufficient demand.
JEDEC sources don't believe there is enough interest within their group to develop an industry standard for the 2.2.2 DIMM. Two years ago, a suggestion was made at JEDEC for such a standard, but it never gained enough support to move forward.