AM2+ and AM3 backwards compatible with AM2
Unfortunately the mix is incompatible the other way round, meaning today’s AM2 CPU’s will not function in AM2+ and AM3 boards. Additionally, AM2+ processors won’t work in AM3 boards due to AM3 lacking a DDR2 memory controller (which AM2+ requires). Moving away from the negatives, this is a great move if you’re a slow upgrader and aren’t ready to farewell your old motherboard.
We learned that for high-performing motherboards, AMD is requiring that AM2+ motherboards support 125W processors using 95A VRM, and that requirement will not change with AM3. When it comes to the mainstream – motherboard makers have to provide 89W using 80 Amper current (80A).