With the increase in motherboards and systems supporting mini-SATA (mSATA) and M.2 standards for SSDs, and increased demand from them being included in more than just portable devices, some frequent problems have been seen by Crucial support, mostly related to basic compatibility.
The single most important thing to remember when dealing with these standards is to refer to your system documentation or a resource like Crucial's System Scanner to check the compatibility of SSDs with your system. Some of these systems require PCIe-based devices, while others require SATA-based devices, and the standards are not interoperable while the pinouts and slots may be similar if not identical. This is the single most frequent issue we see regarding problems with installation of these drives, and it often requires returning a drive so one with the correct compatibility can be used instead.
mSATA drives are relatively straight-forward in terms of compatibility. The only issue we've seen occasionally is users trying to put them into a mini PCIe slot not capable of also supporting mSATA. While the slot is identical, and some motherboards do support both, a PCIe-only slot/motherboard will not run any of Crucial's current offerings, up to and including the MX200 series, all of which are mSATA.
M.2 drives, referred to in some documentation as Next Generation Form Factor (NGFF), feature multiple form factors based on the drive dimensions, layout of NAND components on one or both sides of the drive, and keying of the pins of the drive's connector. Crucial drives currently ship in either a 2260ds (22mm by 60mm, double-sided NAND layout) form factor or 2280ss (22mm by 80mm, single-sided), with B and M keying notches to maximize compatibility. As with our mSATA offerings, all of Crucial's current M.2 drives are SATA-only, so even if dimensions and keying match a PCIe-only socket, the drive will not work. Also, some M.2 slots have different keyings, such as A and E-keying. Crucial's current drives will not fit in these keyed slots, which are usually reserved for wi-fi and bluetooth adapters. The M.2 standard supports many different keyings, though, so this is subject to change with future hardware.
It can't be stressed enough to verify, using your hardware documentation or any other support resources, that your system will support a given drive before purchase. This will save you wasted time trying to diagnose and fix detection problems often being caused by a simple difference in protocol between your socket and storage device, and ensure the easiest installation experience possible.