G.Skill Ripjaws X Series 16 GB (2 x 8 GB) 240-Pin SDRAM (PC3-12800) DDR3 1600 CL10-10-10-30 1.50V Dual Channel Desktop Memory Model F3-12800CL10D-16GBXL at Amazon.com
HP 16 GB DDR3 SDRAM Memory Module 1 x 16 GB 1066MHz DDR3-1066/PC3-8500 Internal Memory 500666-B21 at Amazon.com
48GB (3X 16GB) Matched Pair 1333MHz 240-Pin SDRAM DIMM DDR3 (PC10600) Memory Upgrade Kit for PC Desktops, Mac Pro 'Nehalem' & 'Westmere' (OWC1333D3X9M048) at Amazon.com
G.SKILL F3-1600C9D-16GXM Ripjaws X Series 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory at Amazon.com
48GB (3X 16GB) Matched Pair 1333MHz 240-Pin SDRAM DIMM DDR3 (PC10600) Memory Upgrade Kit for PC Desktops, Mac Pro 'Nehalem' & 'Westmere' (OWC1333D3X9M048) at Amazon.com
G.SKILL Ripjaws X Series 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 2400 (PC3 19200) Desktop Memory Model F3-2400C11D-16GXM at Amazon.com