A couple of rumors hit the web about AMD's upcoming Socket AM4. This new platform will be used by AMD's new processors, it will first be used by Bristol Ridge and later by the first processors based on the new Zen architecture.
This is not official information so I suggest taking it with a grain of salt. The Socket AM4 will reportedly stick with PGA and feature a 1331 pin design, a 33 percent increase versus the roughly 950 pins used by previous AM and FM sockets. It seems AMD wants to keep the size of its chips in check by switching to ?OPGA compared to the normal OPGA they use. This means it wil use a smaller pin diameter, allowing more pins to be crammed together at the cost of weaker pins:
Reducing pin pitch or the distances between pins and staggering pins to fit more in the same space are also two likely strategies. For Intel, a 17% pin count cost 30% in space but moving from 115x to 2011 cost only about 66% size increase. If AMD does it well, AM4 may be compatible with AM3+ and FM2+ heatsinks and not have an overly large package.
The report also mentions that AM4 is expected to support processors with a TDP of up to 140W, which is slightly more than the current maximum of 125W but in-line with Intel's top-end LGA2011 CPUs. AMD's Socket AM4 will be used across the firm's budget, mainstream and enthusiast chips.