Crucial Technology 4GB 240-Pin UDIMM DDR3 Desktop Memory Module, 1.35V, CL=13, Unbuffered, NON-ECC, 1866 MT/S Speed, 512Meg x 64 Crucial 4gb Ddr3 Pc3-14900 Unbuffered Non-ecc 1.35v 512meg X 64 - 4 Gb - Ddr3 Sdram - 1866 Mhz Ddr3-1866/pc3-14900 - 1.35 V - Non-ecc - Unbuffered - 240-pin - Dimm