Stefan Mileschin

Although AMD's upcoming socket AM4 heralds new lines of processors and APUs based on the company's next-generation "Zen" CPU micro-architecture, some of the first APUs will continue to be based the current "Excavator" architecture. The "Bristol Ridge" is one such chip. It made its mobile debut as the 7th generation A-Series and FX-Series mobile APUs, and is en route to the desktop platform, in the AM4 package. What sets the AM4 package apart from the FM2+ package, and in turn "Bristol Ridge" from "Carrizo" is that the platform integrates even the southbridge (FCH) into the APU die. This could explain the 1,331-pin count of the AM4 socket.

http://www.techpowerup.com/221515/am...e-numbers.html