What Else Is An M.2 WiFi Slot Good For?

Many motherboards and laptops these days come with a range of M.2 slots, with only a subset capable of NVME SSDs, and often a truncated subset for “WiFi” cards. Or that’s what they’re usually intended for, but as [Peter Brockie] discovered when looting sites like AliExpress is that you can get plenty of alternative expansion cards for slots that have nothing to do with WiFi.

The reason this should come as no surprise to anyone familiar with the M.2 interface is that each type of “key” specifies one or more electrical interfaces available on that particular M.2 slot. For slots intended for use with NVME SSDs, you see M-keying, which makes 4 lanes of PCIe available. The so-called “WiFi slots” on many motherboards are usually coded for A/E, meaning two lanes of PCIe, USB 2.0, I2C, and a few other rather low-level interfaces. This means that you can connect any PCIe or USB (2.0) device to these slots, as long as the bandwidth is sufficient.

What [Peter] found includes adapter cards that add Ethernet (1GB, 2.5GB), USB 2.0 ports, SIM card (wireless adapter?), fiber-based SFP network adapter, multiple M.2 port adapters to 2+ SATA, tensor accelerator chips (NPUs), and even a full-fledged PCIe M.2 to x16 slot adapter. The good thing about this is that if you don’t care about using WiFi with a system, but you have one of those ports lying around unnecessarily, you can put it to work for Ethernet, SFP, SATA or dongles. other purposes, or just for plugging in internal USB devices.

Clearly, this isn’t a market that has gone untapped for very long, with great prospects for self-designed M.2 cards. Who doesn’t want an FPGA device tucked into a PCIe x2 slot for DIY?

(Thanks to [RebootLoop] for the tip!)