Intel has announced that the SSD Form Factor Working Group has finally come up with a name to replace the long winded SFF-8639 label currently applied to 2.5" devices that connect via PCIe.
As Hardwarezone peeked in the above photo, the SFF-8639 connector will now be called U.2 (spoken 'U dot 2'). This appropriately corresponds with the M.2 connector currently used in portable and small form factor devices today, just with a new letter before the dot.
An M.2 NVMe PCIe device placed on top of a U.2 NVMe PCIe device.
Just as how the M.2 connector can carry SATA and PCIe signaling, the U.2 connector is an extension of the SATA / SAS standard connectors:
Not only are there an additional 7 pins between the repurposed SATA data and power pins, there are an additional 40 pins on the back side. These can carry up to PCIe 3.0 x4 to the connected device. Here is what those pins look like on a connector itself:
Further details about the SFF-8639 / U.2 connector can be seen in the below slide, taken from the P3700 press briefing:
With throughputs of up to 4 GB/sec and the ability to employ the new low latency NVMe protocol, the U.2 and M.2 standards are expected to quickly overtake the need for SATA Express. An additional look at the U.2 standard (then called SFF-8639), as well as a means of adapting from M.2 to U.2, can be found in our Intel SSD 750 Review.