661-3930 1 GB, DDR2 667, ECC, FB-Dimm - Mac Pro 3GHz 8-Core A1186 - 2-2.66-3GHz Quad NB-2219W This is 1GB DDR2 PC2-5300 RAM upgrade for the Mac Pro. This is for PC2-5300 DDR3 Machines. These are DIMM chips and not SODIMM chips used in MacBooks and iMacs. Apple part number: 661-3930