OWC Memory Compatible With Mac Pro Quad Xeon fully meets 's specifications with special attention to proper thermal specifications. 240-pin SDRAM DIMM 2048M x 72, Dual Rank ECC Memory Module Data Rate - 1333MHz Module Bandwidth 10.6GB/s CAS 9-9-9-24 Voltage 1.5V Thermal Sensor RoHS Certified Important OWC Other existing 1GB, 2GB and 4GB modules are not supported for use with these kits and need to be removed when these modules are added. To utilize over 32GB of memory in your Mac Pro using 10.6.x or greater, you must boot into 64 bit mode. In 32 bit mode, all installed memory will show in system profiler but only up to 32GB will be actively used by the computer. About the Thermal Sensor Ensuring maximum performance, reliability and operational feedback - all OWC DDR3 ECC Modules for the Mac Pro 'Nehalem' process models feature utilization of qualified components including the inclusion of the qualified Thermal Sensor EEPROM.