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I found an SBC which has an M2 socket for WiFi cards. It's keying is E.

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I couldn't decide whether I can plug an M2 NVMe SSD into this socket.

Key E normally has PCIe x2, which is not as fast as PCIe x4 for other key types.

But still. Can I attach a standard NVMe SSD to this socket?

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  • \$\begingroup\$ It depends what features the SBC inplements. What does the manual say what it supports or what can you plug in? \$\endgroup\$
    – Justme
    Feb 16, 2023 at 11:13
  • \$\begingroup\$ Seems someone got that working using an adapter. linustechtips.com/topic/… \$\endgroup\$
    – Ben Voigt
    Feb 16, 2023 at 18:50

2 Answers 2

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NVMe cards, as you probably are aware, require an M key slot even through they’re electrically similar to E key, save for the extra 2 lanes. They're set up that way to encourage and support connecting them for maximum performance.

You could adapt type M to type E, and the host should enumerate it properly as a mass storage device when it builds the device tree.

But there is a mechanically better / cheaper / simpler option right in front of you: use a USB3 to NVMe adapter. Yes, it won’t be quite as fast as 2 lanes of Gen 2 PCIe, but it won’t be nearly as fragile as cobbling M.2 adapters together.

Then your M.2 Type E is kept free for the Wifi+BT combo device is was designed for.

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  • \$\begingroup\$ What would be the theoretical max transfer speed of an M-keyed NVMe SSD converted and inserted into a TypeE slot (I guess it's not as fast as when connected to a typeM slot)? \$\endgroup\$
    – Daniel
    Feb 17, 2023 at 14:05
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Assuming the PCIe lanes are wired up, you use a PCIe M.2 card, and you can find a mechanical adapter which works (there are a lot of cheap ones that don't), the yes it can be done.

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