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I am trying to find something that is exceptionally weird and bizarre. I want to use a M.2 NVMe x4 SSD in a PCI-Express x1 slot.

x4 NVMe SSDs directly use PCIe bus protocol, and so can be directly plugged into a full-size PCIe slot using a simple passive adapter. But there are four data lines, so these passive adapters are virtually all x4 lane cards.

By specification, all PCIe cards are backwards compatible with the lowest bandwidth x1 lane slots. If the x1 slot is designed with an open end, it is possible to plug a x16 card into it with 15 lanes hanging exposed in midair and unconnected, and it will work. It won't work well but it will work.

So, what I need is a NVMe x4 passive adapter card, which will plug the M.2 into a normal PCIe x1 slot, and leaves the remaining 3 lanes unconnected.

I have been searching the web on and off for months and have not found anything like this yet.

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After doing some more hunting with weird search terms, I have found a solution in the Amazon Marketplace:

https://www.amazon.com/NGFF-PCIe-Adapter-Samsung-SM951/dp/B01MS64UBB

US$ 34.95 .. a bit expensive for a board with virtually nothing to it, but oh well.

This is the correct non-SATA adapter card, if all it has is the M.2 slot with no chips on the board.

enter image description here

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  • what speeds did you get using the x1 slot vs x4? – malhal Jul 15 '19 at 13:29
  • It varies with the motherboard type, as there are different PCI Express versions. 1.0 1x is 250 MB/s, 2.0 1x is 500 MB/s, 3.0 1x is 985 MB/s, 4.0 1x is 1.969 GB/s, etc. This is faster than the SATA interface for old motherboards. SATA-I is 150 MB/s, SATA-II is 300 MB/s, SATA-III is 600 MB/s. – Dale Mahalko Jul 16 '19 at 16:18
  • I'm aware of the 3.0 1x effective lane speed of 985MB/s I was wondering what you actually got. – malhal Jul 16 '19 at 20:26
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The picture shown is adapter card nvme SSD to PCIE x1 and not x4 though. Theoretically that the SSD will function with 1 lane from the x1 slot but nvme SSD need to fully function from an x4 pcie slot.

But I found a much appropriate adapter card not from a x1 pcie slot but from a x4 slot and supports 1 nvme SSD and 1 m.2 data ssd. But my question is, was the x1 converted to x4?or it's just still x1 allowing the ssds to work at x1 lane? enter image description here

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