16GB 240-pin PC3-8500 (1066MHz) DDR3 ECC SDRAM module for the Early 2009 Mac Pro and Intel Xserve, and some Mac Pro 2010 models.
These 16GB modules use a newer RAM standard (ECC REG) than the 8GB and smaller denominations (ECC NON REG) and they CANNOT be mixed with these smaller modules i.e. if you want to use 16GB modules, you must use ONLY 16GB modules. In the 8 core (8 memory slot) Mac Pros, these modules need to be upgrade in matched pairs. The quad core (4 memory slot) 2009 Mac Pro can only support a maximum of 48GB by fitting three of these 16GB modules and leaving slot 4 empty. The eight core (8 memory slot) 2009 Mac Pro can only support a maximum of 96GB by fitting three pairs of these 16GB modules and leaving slots 4 and 8 empty.
Please note: PC3-8500 modules are fully compatible with the 2009 Nehalem Mac Pro as well as the 2010 Nehalem Quad Core Mac Pros. You may fit these in the Westmere 2010 models however they will run slower than the PC3-10600 modules they are designed to use, and it is not advised to mix PC3-8500 and PC3-10600 modues in the same machine. If you are unsure what modules to use in your machine please check with us before ordering.