DDR4 is the newer generation DDR that replaced DDR3. A compared to DDR3, DDR4 has a lower operating voltage, increased power saving enhancements, as well as increased efficiency and improved chip density.

DDR 2 has clock rate of 200-533MHz, with transfer rates up to 1,066MTps, and a power consumption of to 1.8 volts. DDR3, of course, was an improvement over DDR2. It featured a clock rate of 400-1,066MHz, a...