661-4678 FB-Dimm, DDR2 800, ECC 1 GB - Mac Pro 2.8-3.0-3.2GHz A1186 Early 2008 NB-2218W This is 1GB DDR2 PC2-6400 RAM upgrade for the Mac Pro. This is for PC2-6400 DDR2 Machines. These are DIMM chips and not SODIMM chips used in MacBooks and iMacs. Apple part number: 661-4678