[SOLVED] Confused about why M.2 NVME to PCIe adapters would be more than x4

Cyber_Akuma

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Oct 5, 2002
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I was looking into adapters that let you plug a M.2 NVME into a standard PCIe slot. From what I understand, they are basically PCIe devices so that should be somewhat simple. And there did seem to be tons of devices like this that aren't too expensive, but some of their features confused me.

Take this one for example: https://www.amazon.com/Sabrent-NVMe-PCIe-Aluminum-EC-PCIE/dp/B084GDY2PW/

What confused me is why it's an x16 device when it only holds a single M.2. Aren't all M.2 NVMEs x4 or am I wrong on that? If they are, what benefit does it having the connectors to plug into aX8 or X16 provide since an x4 connector will plug into an X8 or x16 just fine?

There is also this: https://www.amazon.com/ASUS-M-2-X16-V2-Threadripper/dp/B07NQBQB6Z/

This one makes a lot more sense to me, it's also x16 but is supports four NVMEs. So does this mean each one will get x4 or am I still mis-understanding it? Also, I noticed that this one will only work in an x4 or x16 slot as it lacks the notch to allow it to fit in an x8 port. Is there any specific reason for this? Are the any additional pins that connect to anything in place of that notch for an x16 device that allow for something over a connector that is notched for x8 compatibility?

Also from what I understand, there is no guarantee for that second card that anything other than the first NVME will work unless your motherboard supports bifurcating the x16 port you would use into four x4s, or at least two x8s if you want to use two NVMEs? Or did I misunderstand how that works?
 

popatim

Titan
Moderator
1st one fits into those slots; its still a 4 lane card.
If you read the 'about' info, you'll see this: PCI Express Physical interface: PCIe x16/x8/x4 slot. Logical Interface / PCIe Lanes: X4.

2nd one is a true x16 card and will deliver 4 lanes to each M2 slot BUT your motherboard must support a 4-way bifurcation on that Pcie slot for it to work.
 

popatim

Titan
Moderator
1st one fits into those slots; its still a 4 lane card.
If you read the 'about' info, you'll see this: PCI Express Physical interface: PCIe x16/x8/x4 slot. Logical Interface / PCIe Lanes: X4.

2nd one is a true x16 card and will deliver 4 lanes to each M2 slot BUT your motherboard must support a 4-way bifurcation on that Pcie slot for it to work.
 

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