With its next-generation processors and APUs based on the "Zen" micro-architecture, AMD is integrating the chipset into the processor/APU die, making motherboards entirely chipset-free. This on-die chipset, however, is rumored to be facing issues with its integrated USB 3.1 controllers, according to industry sources. AMD sourced the design for the integrated USB 3.1 controllers from ASMedia. The company has a tendency of sourcing integrated controller IP from third-party manufacturers (eg: its SATA controllers and port-multipliers in the past have been sourced from Silicon Image).

Motherboard manufacturers are noticing significant drops in USB 3.1 bandwidths with increase in circuit distances (think wiring running from the AM4 socket to USB 3.1 front-panel headers on the bottom-right corner of a motherboard). Board designers are reportedly having to use additional retimer and redriver chips to get acceptable bandwidths over such ports, and in some cases even entire USB 3.1 controllers, eating into the platform's PCIe budget and escalating costs.

AMD at its pre-Computex media event, showed off the first next-generation socket AM4 processor based on the 14 nm "Summit Ridge" silicon. That processor wasn't alone, it also came with a platform demonstrator for the company's industry partners, behind closed doors. This includes a platform demonstrator motherboard by AMD. Earlier this year, a Chinese tech-site caught a glimpse of this board. There's never anything glamorous about platform demo boards (from either AMD or Intel), they tend to be a haphazard bunch of slots and ports that max out the platform's feature-set. The same applies to this AM4 board.

The picture reveals a few big things about the AM4 socket, and the platform in general. To begin with, the 1331-pin PGA socket is somewhat the same size as AM3+, but likely features finer pins. It features CPU cooler retention holes in a "square" layout, rather than the rectangular layout that AMD has been using way back since socket 754. It will be interesting to see if these mount holes are compatible with any of Intel's sockets. The second and perhaps the biggest change of this platform, of course, is that the chipset is completely integrated with the processor, and so there's no chipset on the board. The processor socket wires out all the connections a southbridge, FCH, or PCH normally would, plus all the I/O of a northbridge (PCIe, memory, etc). The platform supports dual-channel DDR4 memory, and PCI-Express gen 3.0 across its PCIe budget.

AMD CEO Lisa Su, speaking at the company's Computex reveal held up the most important CPU product for the company, the new eight-core "Summit Ridge" processor. A posterboy of the company's new "Zen" micro-architecture, "Summit Ridge" is an eight-core processor with SMT enabling 16 threads for the OS to deal with, a massive 40% IPC increase over the current "Excavator" architecture, and a new platform based around the AM4 socket.

The AM4 socket sees AMD completely relocate the core-logic (chipset) to the processor's die. Socket AM4 motherboards won't have any chipset on them. This also means that the processor has an integrated PCI-Express gen 3.0 root complex, besides the DDR4 integrated memory controller. With the chipset being completely integrated, connectivity such as USB and SATA will be routed out of the processor. The AM4 socket is shared with another kind of products, the "Bristol Ridge" APU, which features "Excavator" CPU cores and a 512-SP GCN 1.2 iGPU.

Noctua is among the first CPU cooler manufacturers to develop a retention kit for the upcoming AMD socket AM4. There are three versions of this, compatible with all existing Noctua coolers, except D0 series and NH-L9i series. This means that even 10-year old heatsinks from Noctua should be able to cool next-gen AMD chips. Noctua will be giving these away for free to all existing customers (proof of purchase required).

Sources tell Bits'n'Chips that AMD could use a common 8-core CPU die based on its upcoming "Zen" architecture over multiple CPU SKUs, at least initially. AMD will have two distinct kinds of processors, those with integrated graphics (APUs) based on the "Bristol Ridge" silicon, and those without integrated graphics (CPUs), based on the "Summit Ridge" silicon. Since products based on both the dies will use a common socket on the desktop (socket AM4), consumers looking for 2-4 CPU cores will be presented with APU options, while those looking for more powerful CPU solutions will be made to choose 8-core CPUs based on the "Summit Ridge" silicon.

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.

The "Bristol Ridge" silicon is likely built on the existing 28 nm process. That's not the only thing "current-gen" about this chip. Its CPU component consists of two "Excavator" modules that make up four CPU cores, with 4 MB total cache; and its integrated GPU will likely be based on the Graphics CoreNext 1.2 "Volcanic Islands" architecture, the same one which drives the "Tonga" and "Fiji" discrete GPUs. The integrated memory controller supports dual-channel DDR4 memory. In its performance benchmarks, an AM4 APU based on the "Bristol Ridge" silicon was pitted against older 6th generation APUs, in which it was found to be as much as 23 percent faster.

More details of AMD's upcoming common socket for both its desktop APUs and high-end CPUs emerged from a recent article by Italian tech-site Bits-n-Chips. To begin with, AM4 will be an µOPGA (pin-grid array), in which the pins will continue to be located on the processor package, and contact points on the socket. The package will be square, and 40 mm in length, making it about as big as a current socket FM2+ package. It will have a pin-count of 1,331 pins, a big increase from the 942 pins of AM3+, and 906 pins of FM2+. AMD could continue to develop LGA sockets for its multi-socket capable Opteron processors based on the "Zen" architecture.

The AM4 platform layout will be functionally closer to that of the FM2+ than the AM3+. Besides the integrated memory controller, the northbridge will be entirely located on the processor die; and so the HyperTransport main system bus will be wired internally. Besides hundreds of electrical pins, the AM4 pin-map will consist of memory I/O, integrated graphics I/O, PCI-Express, and the chipset bus; besides other low-level system I/O interfaces. The memory controller on some of the first AM4 chips, such as "Summit Ridge," will natively support DDR4-2400 MHz, and DDR4-2933 MHz through overclocking.

A lot is riding on AMD's upcoming desktop CPU socket, codenamed AM4. Some of the first motherboards based on this socket are expected to launch in March 2016. What makes the socket particularly interesting (and important) is that it's a transition point for AMD's two major CPU architecture generations - "Excavator" and "Zen." Excavator is an incremental upgrade of AMD's less than successful "Bulldozer" architecture, while "Zen" is its next major one. AM4 is also going to be a common socket for AMD's desktop APU and many-core CPUs.

Some of the first socket AM4 APUs could be "Bristol Ridge." Succeeding the company's "Carrizo" APUs, it will be available in both socket AM4, supporting DDR4 memory, and FP4, supporting both DDR3 and DDR4. This chip will implement "Excavator" CPU cores. In its AM4 avatar, "Bristol Ridge" will offer up to four CPU cores, with TDP ranging between 45W-65W, and with support for DDR4-2400 memory. Later in 2016, AMD could debut its first "Zen" multi-core CPUs, which feature the company's next-gen, performance-focused CPU cores.