Gigaram 4GB (1x4GB) DDR3-1066 ECC DIMM for Apple Mac Pro & Xserve Intel Xeon "Nehalem" (Apple# 1 x MB982G/A) 4GB, PC3-8500, DDR3-1066, 1066Mhz, 8.5GB/s Bandwidth, CAS 7-7-7-20, 5ns Cycle Time, ECC, Dual Rank, RoHS Certified, 512x72, 1.5V, 240pin DIMM. This DIMM module is specifically designed and SPD configured for the "Nehalem" Mac Pro. This DIMM includes the Apple Specified Thermal EPROM Sensor. This module is compatible with the latest Apple Firmware