Originally Posted by el-John-o
Yes, and AM3 socket will work with an AM3/AM2+/AM2 processor, however an AM2+ board will not support an AM3 processor, so it's "upwards compatible"
AM2+/AM3 processors work on AM3/AM2+/AM2 boards that utilize DDR2.
An "AM3 socket" will not handle a AM2+ CPU and older if the mobo is designed to use DDR3.
AM2+ board can support an AM3 given it uses DDR2 and it's VRM can handle it, with the apprpriate BIOS flash if needed.
edit: edited out of confusing myself. Basically it depends on the IMC (AM2+ = DDR2, AM3 = DDR2/3)
and the design of the mobo. If it's an AM2+ (DDR2) board with an AM3 CPU, there must be a BIOS flash and/or the board must be designed to handle the power requirements. If it's a DDR3 board, it only supports AM3.