The M.2 a module are 22 mm wide and comes in a no. of lengths such as 30, 42, 60, 80 and 110 mm. Motherboards are generally handle different length M.2 modules however 80 mm is the typical size for a flash memory module. Wireless adapters are frequently found on shorter modules. A motherboard doesn’t support all lengths.
A motherboard can fit in a range of key M.2 socket options. The trendiest are B and M. The B interface offers SATA, x2 PCIe, HSIC, SSIC, I2C, USB 2.0/ 3.0, audio, UIM and SMBus support. The M interface give x4 PCIe, SATA, and SMBus. The sockets are keyed thus a module cannot be plugged into a socket which doesn’t support the module’s interface. M.2 modules are keyed to fit sockets which will support the interface used by the means of the module.
SATA modules like SanDisk’s X400 generally have a B and M edge connector which allows them to plug into a B or M socket. The 80 mm long X400 cling up to 1 TB of flash memory. It is a single side M.2 module which is only 1.5 mm high. The 256 GB version is rated at 40 GB/day for 5 years. It employs SanDisk’s 6th generation X3 Technology. M.2 modules with a x4 PCIe interface must have a M connector.
The main differences between the x4 PCIe or NVMe interface and the SATA interface are bandwidth and overhead. A single PCIe 3.0 path can handle a 6 Gbit/s SATA 3.0 interface. There is also less transparency with a direct PCIe interface.
Device drivers usually insulate applications from the underlying hardware which allows designers to decide the appropriate hardware for the app and processor balancing performance, capacity and the cost. One or more M.2 sockets can be establishing new motherboards. An M.2 module can be the primary storage device eliminating the requirement for more conventional hard disk or SSD drives.