The new AM3 Socket:
Even though the new Phenom II processors use the AM3 socket, they are backwards compatible and can be fully utilize with the existing AM2+ socket. This is achieved by a controller within the processor which allows it to use either DDR2 or DD3 Memory.
What does this mean for you? Let’s say that you have an AMD Phenom or Athlon processors with DDR2 memory and want to upgrade your computer, but you can’t afford the entire computer now. Well you can purchase one of these new AMD Phenom II processors, and when put it in your current system it will work perfectly. This will allow you to upgrade your computer little by little, rather than picking up one of the Intel’s i7 processors which will require you to upgrade your processor, motherboard, and memory.