PCIe 3x2 SSD on PCIe 2x4 slot

If I plug a PCIe 3.0 x2 NVMe SSD to a PCIe 3.0 X4 to M.2 adapter and plug that in to a PCIe 2.0 X4 slot, will the SSD running at full speed or down to PCIe 2X2 speed?

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I would say this. But I have no experience.

Why are you going to do all of this?

Or is this just theoretical?

Still in planting phase. I have ZFS storage server on X8 chipset, so only PCie2.0. Want to add L2ARC/SLOG to the server without using the storage bays.

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Ahhhh. I see.

Link to adapter in question?

If I recall correctly, pcie 2.0 and 3.0 are electrically identical, so…

If it’s wired electrically as an x4 adapter, it should pass through x4 lanes to the m.2 socket. They’ll be pcie 2.0 x4 though so your drive is expecting pcie 3.0 x4 and getting half the bandwidth despite x4 lanes.

That shouldn’t have any impact on your intended application I’d wager.

Any adapter, as long as it works I guess…

PCIe 3x2 SSD use different keys, so it may only use the X2 traces on the PCB.

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:blush: I missed that in the OP, it’s an x2 drive so electrically it will always be x2, no way around that. still half bandwidth since 2.0 vs 3.0

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What if I use this adapter.
It has AS Media controller between the PCIe slot and M.2.

Interesting … kinda spicy at $200 just to add two ssd’s. Do you have x16 slot to park it in?

I think I paid around $25 for my x4 nvme to x16 pci-e adapter from Amazon, even came with a heatsink.

Yes, that is really pricey, more than what I paid for the whole server…
I will never buy that adapter but just an idea.

The motherboard has dual 5520 chipsets so plenty PCIe slots.

Looks like I may choose PCIe 2.0 to dual SATA or maybe quad mSATA if I can find low price for 250GB+.

If you’re going SATA, how about a plain 'ol host bus adapter? 2.5" SSDs can live a lot of places, they don’t need to hog drive bays for larger drives. Depending on your chassis you could do 2, 4 maybe more sticky taped to the back of the motherboard tray

It’s in a Supermicro CSE-836 case. It does not have much room to stick the 2.5 drives to, and cable management will be a nightmare.

Have you seen this?


Use a sff-8087? Fan out cables to keep the cables clean

Kind off topic now. Thanks everyone for the help. I will post more about my server setup in the not too distance future.

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