RAM & Memory Upgrades
OWC 48.0GB (3 x 16GB) PC8500 DDR3 ECC 1066 MHz 240 pin DIMM Memory Upgrade Kit for 2009 Mac Pro and Xserve
Capacity: 48 GB Timings: CL7 7 – 7 20 Module: 3 Stück Standard: DDR3-1066 (PC3-8500) Voltage: 1.5 volts
https://www.bizrate.co.uk/ram_memoryupgrades/owc-48-0gb-3-x-16gb-oid36663867564.html