OWC 2.0GB PC8500 DDR3 ECC 1066 MHz 240 pin DIMM Memory Module Upgrade for Mac Pro and Xserve 2GB 240-pin SDRAM DIMM 256 x 72, Dual Rank ECC Memory Module, 1066MHz, CAS 7-7-7-20, 1.5V, RoHS certified, 8.5GB/s Perfect for the Mac Pro 8-core and Mac Pro Quad-core Xeon systems For Mac Pro Early 2009 & Late 2010 'Nehalem' & 'Westmere' systems and Early 2009 Xserve, Compatible with PC desktops and PC Servers with Intel / AMD Process based PCs capable with the specifications listed above. Memory complies with JEDEC Specifications, document JESD79-3B Compatible with: Mac Pro 8-Core (Mid 2010 Model ID:MacPro5,1 (2.4GHz)), Mac Pro (Mid 2010 Quad-Core Model ID: MacPro5,1 (2.8GHz, 3.2GHz, 3.33GHz)), Mac Pro (Early 2009 8-Core Model ID:MacPro4,1 (2.26GHz, 2.66GHz, 2.93GHz)), Mac Pro (Early 2009 Quad-Core Model ID: MacPro4,1 (2.66GHz, 2.93GHz, 3.33GHz)), Xserve 8-Core (Early 2009 Model ID:Xserve3,1 (2.26GHz, 2.66GHz, 2.93GHz)), Xserve Quad-Core (Early 2009 Model ID:Xserve3,1 (2.26GHz)) OWC Memory Lifetime Limited Warranty including Advanced Replacement Program Mac Pro 8-Core (Mid 2010)(July, 2010) Model ID: MacPro5,1 (2.4GHz) Mac Pro (Mid 2010 Quad-Core)(July, 2010) Model ID: MacPro5,1 (2.8GHz, 3.2GHz, 3.33GHz) Mac Pro (Early 2009 8-Core)(March, 2009) Model ID: MacPro4,1 (2.26GHz, 2.66GHz, 2.93GHz) Mac Pro (Early 2009 Quad-Core)(March, 2009) Model ID: MacPro4,1 (2.66GHz, 2.93GHz, 3.33GHz) Xserve 8-Core (Early 2009)(April, 2009) Model ID: Xserve3,1 (2.26GHz, 2.66GHz, 2.93GHz) Xserve Quad-Core (Early 2009)(April, 2009) Model ID: Xserve3,1 (2.26GHz) PC Desktops: Compatible with Intel / AMD Process based PCs capable with the specifications listed above. PC Servers:Compatible with Intel / AMD Process based servers capable with the specifications listed above <span class="a-text-bold">Size:</span>2GB (2048MB) 240-pin SDRAM 256M x 72, Dual Rank ECC Module Data Rate = 1066MHz Module Bandwidth 8.5GB/s CAS 7-7-7-20 Voltage 1.5V JEDEC Spec JESD79-3 Fully compliant with all Apple Mac Pro Specifications Apple Specified Thermal Sensor