Lennart Sorensen wrote: > Well I have only really been looking at desktop systems. > Looking at the Asus Z97 line for example
You mean you've been looking at mainboards. ;) BTW, Asus is a poor example of an OEM, because most of their products are now fabbed two (2), different, external ODMs (ECS and Foxconn).** Mainboards are a crapshoot of non-standards, and worse than notebooks. I.e., even most Tier-2 notebooks, and even some Tier-1 brands/models (e.g., Alienware, etc...) use the same ODM (Clevo). > 10 variants do PCIe and SATA, > 5 do only PCIe (one of which is PCIe x4). If you have _true_ PCIe x4 (and SATA), then it has to be a "M" card and socket. Although there is soft logic to prevent most issues, most B+M dual-types are actually only PCIe x2 (plus SATA) for a reason. They avoid the other traces that B offers for USB, audio, etc... But mainboards are a crapshoot, and you'll get a lot of non-standards. > Quite a few M.2 cards are SATA only Nearly all are. That's because the first "native" PCIe NAND controllers were only fabbed in the last few months, and still being "sampled." The few M.2 PCIe cards out are using a yesteryear, external PCIe 2.0 bridge chip fabbed at old 65-90nm technologies. They were not designed for the type of throughput NAND is capable of. I.e., Most high-speed PCIe devices have their PCIe controller built on-package, if not on-die with the ASIC. E.g., Mellanox fabs most of the "unified" ASICs used in network-controller NICs/HBAs (Eth, FC, IB) > and hence don't work on such a board that has one PCIe > of course. There have been a lot of issues with mainboards doing stupid things to the point I won't trust the first generation. I.e., I'm going to stick with a PCIe adapter card that to adapt a M.2 B/M type card so it does both PCIe x4 (or x1 if in a x1) and SATA. > Supposedly with the latest UEFI version and a 'hyper kit' > adapter, those PCIe enabled M.2 slots on the asus board > also natively run NVMe with a mini SAS connector. You mean SATA-Express? It's not really related to M.2 ... at all. I.e., M.2 (and PCIe "expansion cards") already have PCIe traces. The SATA-Express is so you can "cable in" the PCIe traces. ;) E.g., so 2.5" form-factor NAND devices can use PCIe. -- bjs -- 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
