Spinoff benefits from DDR3

In taking a look at benchmarks run on Tom’s Hardware, Steve Leibson on the Denali Memory Blog reckons DDR3 could be more important for embedded applications than for PCs.

According to Leibson, Patrick Schmid and Achim Roos found that “the use of low-voltage DDR3 SDRAM cut system power by about a watt at idle and by as much as three to six watts at peak operating loads”.

Leibson adds: “When the overall system dissipates well more than 100 Watts, as do most high-end multicore PCs, the relative power saving from low-voltage DDR3 SDRAM isn’t much. However, designers of mobile and wireless embedded systems that employ low-power processors try to squeeze every milliwatt out of the system design to prolong battery life and talk time, so a few Watts of power savings is a very big deal indeed.”

Power consumption in memory has become a bigger concern in servers than with desktop PCs as well, thanks to all the publicity around the massive air-conditioning costs of server rooms. Memory makers have been responding to this.

Three years ago, Micron tweaked its DDR2 design for servers before DDR3 got going, lowering voltages to get better power ratings. Spansion has also had a go with trying to get more flash into server blades as an additional tier in the memory hierarchy.

The trouble with memory is that when you go off-piste with a new architecture for a specialised use, people get nervous about being locked in to a potentially more expensive and difficult-to-source component. Staying on the main path is often less risky, if sometimes less efficient.

Being able to use DDR3 to cut power in portable embedded designs is welcome news. Hopefully, future architectures will do more of this as the needs of the PC begin to align with those of lower-power devices.

Posted by Chris Edwards

The Low-Power Design Blog is sponsored by Mentor Graphics. The company has focused years of R&D on low-power design techniques and is glad to support a resource that highlights creative methods for reducing the power consumption of electronic systems.