Unfortunately you cannot get an APU processor (FM1 or FM2) with 8 cores, those only come in 2, 3 or 4 cores. The built-in graphics on these chips are pretty impressive, however if your into gaming you will be disappointed unless you pair up a matching video card and essentially run crossfire.

You can however go with a different socket AMD to get 8 cores, that being said however Intel's proc's have hyper-threading which allows it to run 2 threads per core. As far as your OS is concerned that means that an quad core I7 is seen as and functions as an 8 core. You can also get 6 core I7's which would be like having a 12 core. Or you can go with server hardware and get an AMD opteron 16 core proc.

This is a pretty good site for information on hardware (tomshardware)