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DDR3 - The Basics
DDR3 SDRAM stands for Double Data Rate 3 Synchronous Dynamic Random Access Memory. This kind of memory is an advancement over its predecessor, DDR2 SDRAM, in several ways. Firstly, it is purported to have reduced power consumption by 40% compared to the previous version. This is achieved through technology within the chip allowing for a lower operating current, and is supported by the introduction of special transistors which reduce current leakage.

It also boasts improvements in other areas, such as a larger prefetch buffer and higher data transfer clock rate. In the most basic of terms, it is theoretically about twice as fast at data transfer than DDR2, whilst using only 83% of the energy. The current specifications are not yet finalized for the finished product, however prototypes were created in early 2005 for review, with Intel currently saying they should be ready to support the chip towards the end of 2007, and AMD expecting to be in a similar position for 2008.
 
DDR - Features and Specifications

The DDR3 SDRAM modules will contain the following features:

  • An asynchronous reset pin, introduced for the first time in such modules. This is faster than the synchronous reset signals used previously, as it does not rely on the chip's clock.
  • System level flight time compensation is supported.
  • On-DIMM Mirror friendly DRAM ballout.
  • CWL (CAS Write Latency) per speed bin is also a newly introduced component.
  • On-die IO calibration engine is included.
  • As is READ and WRITE calibration.
  • Each DDR3 SDRAM module includes fly-by command/address/control bus with On-DIMM termination.
  • Each module also includes high precision calibration resistors.
  • Modules are to be shipped in densities ranging from 512Mb to 8Gb, primarily focused on 512 Mb and 1Gb densities to begin with, the industry believing that larger modules will eventually become available for specialized applications such as servers.
DDR3 - The Benefits

The most noticeable advantage that DDR3 memory has over its predecessors is that it is much faster, running at up to twice the speed of previously released SDRAM. The bandwidth is much increased, from DDR2's 400-1066MHz to a single clock bandwidth range of 800-1600MHz for DDR3. This improvement is supported by a doubling in the size of the prefetch buffer, from DDR2's 4-bit to DDR3's 8-bit.

Despite this increase in power in terms of application, the power required to run the RAM has actually been reduced, by as much as 40% compared to the previous model. DDR3 utilizes what is known as 90nanometer fabrication technology, which allows it to operate at lower currents, reducing the voltage requirements from 1.8V to 1.5. In addition another feature, Dual-Gate transistors, reduces the leakage of current. These power-saving features work together to reduce the heat created by the module, improving performance and the longevity of batteries and the components themselves.

In short, the benefits to this memory are as follows:

  • Higher bandwidth.
  • Lower power consumption with improved performance.
  • Longer battery and component lifetime due to improved thermal design.