OWC 16GB (4x4GB) DDR3 ECC Unbuffered CL7 PC3-8500 1066MHz SDRAM Memory Ram Upgrade Module Compatible with 2009-2010 Mac Pro Nehalem, Xserve 2009 (OWC85MP3W4M16GK)

Product Specs: 4GB (4096MB) : 240-pin : SDRAM DIMM 512M x 72, Dual Rank ECC Memory Module : Data Rate = 1066MHz : Module Bandwidth 8.5GB/s : CAS 7-7-7-20 : Voltage 1.5V : Apple Specified Thermal Sensor* : RoHS Certified : Free Installation Videos & Manuals : OWC Memory Lifetime Limited Warranty including Advanced Replacement Program : OWC Memory for Mac Pro Quad Xeon fully meets Apple's specifications with special attention to proper thermal specifications.