8GB G.Skill DDR3 PC3-10666 1333MHz Ripjaw Series CL9 (9-9-9-24) Dual Channel kit at Amazon.com
Amazon.com: OWC 32.0GB (4X 8GB) DDR3 ECC PC10600 1333MHz SDRAM ECC, Compatible with Mac Pro (OWC1333D3W8M32K) : Everything Else
HyperX 8GB 1600MHz DDR3 PC3-12800 CL10 DIMM Desktop Memory, Black KHX16C10B1B/8 at Amazon.com
Silicon Power Hynix IC Compatible for Apple DDR3 DDR3L 16GB (2 x 8GB) RAM 1600MHz (PC3 12800) 204 pin CL11 1.35V Non ECC Unbuffered SODIMM Laptop Notebook Memory RAM Module Upgrade at Amazon.com