Axiom 16GB DDR3-1600 SODIMM Kit (2 x 8GB) for Apple MD634G/A, ME167G/A (PC3 12800) MD634G/A-AX Powerful performance - DDR3 nearly doubles the speed of DDR2 by offering faster data rates Low Power Consumption - DDR3 operates on a reduced supply voltage thanks to its efficient design. Higher Bandwidth and Density - DDR3 allows better computer performance thanks to the fastest data transfer rates available.