What is DDR2/ DDR3?

DDR3 is the newest memory in the DDR generation, and just like its predecessors it cannot be mixed with older versions.

DDR2 is the current generation in DDR memory. It's just one of several new developments that promise to increase the speed of personal computers.

DDR2 is, however, incompatible with existing DDR motherboards. DDR2 modules have a special "notch" in the connector that will only allow them to be installed in a DDR2 compatible motherboard.