Bryan J Smith wrote: > Very few issues with PCIe v. SATA when it comes to M.2. > I.e., > - Virtually all M.2 notebooks have at least one (1), dual-keyed B-M socket > - Virtually all notebooks have all their M.2 B-M sockets wired to SATA > - Virtually all notebooks have at least one (1) M.2 B-M socket wired to PCIe > - Virtually all M.2 storage cards are also dual-keyed for B and M (x)
I probably should have clarified this for those unfamiliar with M.2 ... _Both_ B and M support _both_ SATA and PCIe. B provides SATA + PCIe x2 M provides SATA + PCIe x4 That's why you'll get _both_ cards _and_ sockets that are dual-keyed. It's not PCIe v. SATA ... they _both_ each support _both_. Since SATA is "cheap" -- both port-wise (6-8 in any chipset, heck, 4 on some CPUs) and trace-wise (4 + 3 GND) -- virtually every single notebook will connect a SATA port to every single B and/or M socket. That is not always the case with PCIe, where they may only connect to one (1). But they almost always have at least one (1) that is wired to PCIe. E.g., many low to mid end notebooks only provide four (4) PCIe traces, so they will either split out x2 to two (2) or one (1) x4. Some really low-end ones may only provide x2 or even x1. I only pointed out the "E" type because you will find that, especially if the notebook advertises three (3) M.2 slots, that it's really PCIe + UART. E.g., WiFi card plus optional broadband. -- bjs P.S. You might now be asking, why did the make separate B and M? B has less PCIe traces because it also supports USB, audio and other things. M is a pure PCIe + SATA type. You're going to find most notebook "storage" sockets are actually just a M slot, even if they only provide x2 (or even x1) traces, to the x4 reservation. -- Bryan J Smith - http://www.linkedin.com/in/bjsmith _______________________________________________ lpi-examdev mailing list [email protected] http://list.lpi.org/cgi-bin/mailman/listinfo/lpi-examdev
