U.2 (pronounced Udot2, lest Bono exercise legal force) has made a major appearance on PC platform updates from motherboard vendors, including Gigabyte with new X99 and Z170X motherboards at PAX. The form factor used to be called SFF-8639 (SSD Form Factor) and was targeted almost entirely at server and enterprise markets. In a move toward greater user-friendliness, the interface has rebranded as “U.2,” easier to remember with the M.2 interface also proliferating across the market.

This “TLDR” article explains the U.2 vs. M.2 vs. SATA Express differences, with a focus on PCI-e lane assignment and speeds or throughputs.