IDF Fall 2004: Dual Core, Virtualisation and Power Saving
 

Their first demonstration used two almost identically configured Xeon systems, one using DDR-II memory, the other using DDR, in a large density. The DDR-II-equipped system had a power draw some 100W less than the same DDR-equipped system. Spread over a large number of machines in your organisation and just the switch in memory types can save you lots of money and help with thermal design issues and other heat-related problems.

Link: http://www.hexus.net/content/reviews...lld19JRD04NjQ=