
Originally Posted by
ASUS M4A79 Deluxe review
You see, Socket AM2+ Athlon X2 and Phenom processors have 940 pins and their integrated memory controllers can support up to DDR2-1066MHz RAM. Meanwhile, the the new Socket AM3 CPUs use 938 pins and are pin-compatible (i.e. they fit) with AM2+ sockets. They also have memory controllers that support both DDR2-1066MHz and DDR3-1333MHz system memory. The result is you should, in theory, be able to use the new AM3 CPUs in existing AM2+ motherboards, just with the limitation that you'll only be able to use the DDR2 memory that these older motherboards support. Oh, and you'll almost certianly need to update your motherboard's BIOS.