G.SKILL Ripjaws Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model (F3-12800CL9D-8GBRL) at Amazon.com
OWC 8GB PC3-12800 DDR3L 1600MHz SO-DIMM 204 Pin CL11 Memory Module Upgrade Compatible with iMac, Mac Mini, and MacBook Pro (OWC1600DDR3S8GB) at Amazon .com
8GB (2 X 4GB) DDR3 1600MHz PC3-12800 240-pin Memory RAM DIMM Kit for Desktop PC by NEMIX RAM at Amazon.com