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Introducing to DDR2 SDRAM

This is the latest advancement for DDR technology. Personally, I don't think it is an option for people who want to upgrade their existing system.

DDR2 SDRAM uses a new form factor, a 240 pin DIMM (Dual Inline Memory Module) which is not compatible with current DDR memory slots.

Currently, DDR2 is only supported by motherboards that have CPU socket 775 (LGA775) and latest chipset Intel 925XE, Intel 915G, Intel 915P. These new chipsets employed in LGA775 systems were designed for the new memory type, DDR2 SDRAM. Upcoming chipsets by Intel and other manufacturers will support DDR2 specifically, and are not backwards compatible.

There is little demand from upgrading from DDR1 to DDR2 as the owner needs to replace almost every part in the PC. It just do not make much economic sense.

Even if you are interested in building up a new system, you should be aware of the price difference. Is the newer LGA775 CPU more costly? The motherboard is slightly more expensive and the price of DDR2 is definitely higher than the DDR counterparts. Well prices for hardware may change, so these newer technology components may cost less in the near future.

So why are Intel and other manufacturers introducing DDR2? It promises higher performance, supports greater clock frequency and delivers higher bandwidth. The existing DDR SDRAM can move data across the system bus two times per clock. This already doubles the old SDRAM. DDR2 SDRAM doubles the data transfer amount again by performing four transfers per clock.

There is no major electronic part advancement in DDR2 as it uses the same type of memory cells as DDR1. But by using multiplexing technique (some electronics engineering design principle), it is able to double the bandwidth. In the early stage of the design, DDR2 SDRAM has higher access latency (meaning slower access), but now it is changing and improving.

DDR2 SDRAM will use 1.8 Volts for power. This is a considerable drop from the 2.5 volts used by conventional DDR memory, and should result in cooler and less power hungry memory modules.

Base on electronics theory, lower voltage means less time needed for it to swing between no voltage, the signalling voltage, and then back again. Hence lower signaling voltage allows for higher clock frequencies.

DDR SDRAM production currently stops at 400MHz, also described as PC3200. DDR2 picks up from there. DDR2 will be available at 533MHz DDR, 667MHz DDR and 800MHz DDR specifications.

In term of capacity, DDR2 SDRAM will start off at 256MB, with 512MB and 1GB available.

To summarize, DDR2 SDRAM belongs to the next generation of PC technology which Intel and other manufacturers are trying very hard to push. Sooner or later, you will see LGA775 CPU (Socket 775), PCI-Express, SATA and DDR2 floating around in the Sim Lim Square. PC technology advancement never ends!