Crucial Technology CT2CP51272AP667 8 GB (4 GBx2) Apple Specific DDR2 PC2-5300 CL=5 Fully Buffered ECC DDR2-667 1.8V 128Meg x 72 Memory Kit Apple Mac Pro (8-core) Desktop/PC An FBDIMM will not fit into a standard DDR2 socket, and a DDR2 module will not fit into an FBDIMM socket.