RAM & Memory Upgrades
OWC 16.0 GB (2X 8GB) PC8500 DDR3 ECC 1066 MHz 240 pin DIMM Memory Upgrade Kit for 2009 Mac Pro and Xserve
OWC Memory Upgrade Kit: 16.0GB Memory Matched Set (2x 8GB) PC-8500 1066MHz 240 pin DDR3 ECC SDRAM Modules For Mac Pro Early 2009 & Late 2010 'Nehalem' & 'Westmere' systems and Early 2009 Xserve, Compatible with PC desktops with Intel / AMD Process...
https://www.bizrate.co.uk/ram_memoryupgrades/owc-16-0-gb-2x-8gb-oid6884243141.html