AMD has launched its Ryzen-based take on x86 server processors [anandtech.com] to compete with Intel's Xeon CPUs. All of the Epyc 7000-series CPUs support 128 PCIe 3.0 lanes and 8 channels (2 DIMMs per channel) of DDR4-2666 DRAM:
A few weeks ago AMD announced the naming of the new line of enterprise-class processors, called EPYC, and today marks the official launch with configurations up to 32 cores and 64 threads per processor. We also got an insight into several features of the design, including the AMD Infinity Fabric.
Today's announcement of the AMD EPYC product line sees the launch of the top four CPUs, focused primarily at dual socket systems. The full EPYC stack will contain twelve processors, with three for single socket environments, with the rest of the stack being made available at the end of July. It is worth taking a few minutes to look at how these processors look under the hood.
On the package are four silicon dies, each one containing the same 8-core silicon we saw in the AMD Ryzen processors. Each silicon die has two core complexes, each of four cores, and supports two memory channels, giving a total maximum of 32 cores and 8 memory channels on an EPYC processor. The dies are connected by AMD's newest interconnect, the Infinity Fabric, which plays a key role not only in die-to-die communication but also processor-to-processor communication and within AMD's new Vega graphics. AMD designed the Infinity Fabric to be modular and scalable in order to support large GPUs and CPUs in the roadmap going forward, and states that within a single package the fabric is overprovisioned to minimize any issues with non-NUMA aware software (more on this later).
With a total of 8 memory channels, and support for 2 DIMMs per channel, AMD is quoting a 2TB per socket maximum memory support, scaling up to 4TB per system in a dual processor system. Each CPU will support 128 PCIe 3.0 lanes, suitable for six GPUs with full bandwidth support (plus IO) or up to 32 NVMe drives for storage. All the PCIe lanes can be used for IO devices, such as SATA drives or network ports, or as Infinity Fabric connections to other devices. There are also 4 IO hubs per processor for additional storage support.
AMD's slides at Ars Technica [arstechnica.com].