Is my M.2 connected over SATA or PCIe???

Dear Experts

I have a Thinkpad W540. It has an M.2 slot. The slot was initially designed for the WAN card but I have seen people use it with SSDs. M.2 slots that are used for WAN (and the Wifi Card) are usually connected via PCIe. However, I'm not sure it is a PCIe nor what kind of PCIe connection?

Is there a way I can check whether the M.2 is connected to SATA or PCIe?

I want to load a fast SSD if it is a PCIe connection.

My model is a W540 and 20BHS16L00. I have included some data below that might be of help:


Here are links to Device Manager images.

(I did not paste all 8 CPU Threads)

Also here is the user guide: http://

4 answers Last reply Best Answer
More about connected sata pcie
  1. On page 129 of the guide (error codes) it makes reference to "M.2 SATA device" so that's probably the answer
  2. emmjawsX said:
    On page 129 of the guide (error codes) it makes reference to "M.2 SATA device" so that's probably the answer

    Possibly, but not necessarily. The typical M.2 connector design supports both SATA and PCIe connection protocols for compatibility. If the socket is B-key, it supports PCIe x 2 AND SATA, if it is M-Key, it supports PCIe x 4 AND SATA. It provides for both newer protocols and legacy SATA III speeds for compatibility purposes. It's possible that when the manual was printed there were only M.2 SATA based devices available as NVMe has only started to take off recently.

    What you need to know is the socket keying - if it is a B+M key, then it should support both PCIe x4 and x2, and SATA drives. Plus, you'd need the NVMe support for a PCIe based drive. In general, if you need to make sure it's compatible and absolute blazing speeds aren't needed (as in 500MB/sec or so is sufficient), a SATA based B-key drive would be the safe choice.
  3. Best answer
    FYI, most of what I've seen suggests that while (NVMe) PCIe SSDs are a lot faster on paper and in benchmarks, they're not really noticeably better in typical consumer use compared to regular SATA SSDs.
  4. Grab a program called HwInfo. It comes as an installer or a zip file. When you run it there will be a window with many drop downs on the left (kinda like device manager). Click "motherboard" and post an image of what pops up on the right.
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