Affordable 25g sfp28 or 100g qsfp56 nic

Hardware Hub Networking
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Hi I want to have a dual 25g sfp28 nic. It will be going into slot 3 on my x670e proart which is pcie 4 x4 lanes on a physically x16 slot. Or a single 100g qsfp56 if i went with the x8 plan below?

I’m finding it hard to see anything affordable which will work when limited to x4 lanes?

It’s going to be used for some load testing on a small ceph cluster so this pc is temporarily going to be used to try stress the cluster as a client.

Another option would be to relocate my gpu and then i’d have x8 lanes available for a network card if it’s not possible to find a dual 25g nic which operates at pcie 4 x4

I think pcie 4 x4 should be enough for 64gbit so dual 25 should be fine (if the card negotiates down to x4 properly).

Thanks for any help pointing me in the right direction.

Not sure what it will be used for after testing but i’d like to be able to leave it in the pc so I’m leaning away from the option where my gpu would be stuck at x8, instead of using the chipset pcie x4 slot.

Thanks

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Define “affordable”. For the most part a NIC like you are describing is hardware designed for enterprise use, thus manufacturers don’t consider cost and will have a higher MSRP.

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Thanks I’m open to second hand and strange cards that might need firmware flashed etc to work to make it cheaper. I don’t know the budget because it will depend on what is available.

If I get some idea of which cards successfully operate at pcie 4 x4 then i could choose the cheapest one

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dual port 25GbE connectx-4 lx are around 30 bucks on ebay.

I have mine plugged into an x4 slot but I haven’t tried 25GbE yet.

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So far I have found this

€175 ebay - Intel E810-XXVDA2 - 2x sfp28 - x8 pcie 4.0

I am unsure how it performs at x4 but its reasonable to assume it will work since there’s enough bandwidth on x4 pcie 4

Reference here says it runs at full speed on x4 but its untested. I think I might try this one.

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I think the lowest end card you can get is a ConnectX-5 MCX512A-ADAT. The main thing is that most cards are PCIE 3, and you need a PCIE 4 NIC to make the bandwidth work. So that limits you to a single card of the CX-5 line, or go with a CX-6 or Intel E810 card. I believe those are your only real options. I just dont know if they actually function on an x4 slot (I think they should) or if they will give some boot error.

100gb is pointless, as a PCIE 4 x4 slot only has roughly 61gbit of bandwidth each way on it. I wouldnt relocate your GPU to the x4 slot as that would likely be too limiting on it.

So options are:
MCX512A-ADAT (the more common ACAT is PCIE 3)
MCX631102AN-ADAT
MCX621202AC-ADAT (crypto enabled)
E810-XXVAM2 / E810-XXVDA2 (DA2 is Intel made card, AM2 is the main chip but can be put on a 3rd party made NIC)

E810-CAM2 (100gb that is compatible with cheap 100gb switches)

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I have an Intel E810-XXV-2, works in Linux (Debian 12) and Windows 10 without hickups.

Running FS-branded SFP28-transceivers in there.

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