Memory modules will run at optimal speed and voltage depending on processor model and number of modules installed.
DDR3 1600MT/s Non-ECC Unbuffered SODIMM CL11 1RX8 1.35V 204-pin 4Gbit
DDR3 1600MT/s Non-ECC Unbuffered SODIMM CL11 2RX8 1.35V 204-pin 4Gbit
DDR3 1600MT/s Non-ECC Unbuffered SODIMM CL11 2RX8 1.5V 204-pin 4Gbit
DDR3 1600MT/s Non-ECC Unbuffered SODIMM CL11 1RX8 1.5V 204-pin 4Gbit