XXV710 not visible when connected via an M.2 adapter

[piranha32]

Hi!

I use and M.2-oculink-PCIe adapters to hook up a 10G card to ASRock B850I Lightning WiFi motherboard. The adapters are from this set: https://www.amazon.com/dp/B0CRR7HMX5?th=1 and this is the Oculink cable: https://www.amazon.com/dp/B07TG9DK4W?th=1
I'm using the M2_2 port, which is connected to the chipset. The PCIe adapter is powered using 4 pin 12V cable.

I use this setup with x520 without problems (single port), but I can't get XXV710-DA2 to show up on the bus. The card works fine when installed in a PCIe slot in another computer, the power LEDs are lit on the adapter board. I tried all possible jumper and switch combinations on the Oculink-PCIe board, but it did not help. All components are supposed to be PCIe 4.0 compliant, and XXV710 uses PCIe3, so hopefully this is not the problem. Unfortunately I can't force PCIe version in this M.2 slot. Is there anything else I could try to make the card work?

 

[CyklonDX]

i've got one x710-t2l over m.2 on msi x570 unify;

if you have some x4 pcie bus on mobo try your card there - if it fails well - that might be it. *(maybe bios option to limit your main pcie to x4?)
Note this:

Re:XXV710-DA2 and Z590 chipset

Hello lopess1971, I hope you're doing good! Please be advised that this request is still escalated to our engineers. Once we received an update from them, we will relay it to you. Please expect another update no later than 3 business days. Thank you for your kind understanding. Best...

community.intel.com

You might have better luck with mellanox or broadcom cards.

 

[piranha32]

I tested the card in GPU slot: works, regardless of PCIe link speed settings.
I also checked the link status information provided by lspci:

Here's the data for x520 running at gen2 speed in the oculink adapter:

                LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis-
                         Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
                         Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
                LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
                         EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
                         Retimer- 2Retimers- CrosslinkRes: unsupported

Here's the same section for xxv710 in the PCIe slot:

                LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
                         Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
                         Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
                LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete+ EqualizationPhase1+
                         EqualizationPhase2+ EqualizationPhase3+ LinkEqualizationRequest-
                         Retimer- 2Retimers- CrosslinkRes: unsupported

Does the -6dB de-emphasis level in LnkSta2 for x520 mean that the link is hitting the limits?

EDIT: I just noticed that target link speed in LnkCtl2 for xxv710 is 2.5GT/s. LnkSta says that the speed is 8GT/s.

 

[CyklonDX]

what i mean try running the card in electrically x4 pcie lane.

also look at the golden plated pins - if you see discoloration or scratches your card - may be the case first 2-4 lanes are shot - and it only works when slot has full 8 electrically lanes. *alternatively you can get pcie lane tester.

 

[piranha32]

I did a few more experiments:
- 3070 in the Oculink adapter: works at gen4 speed
- xxv710 in an m.2-to-pcie x4 adapter (not oculink): works, but... LnkCap2 and LnkCtl2 report 2.5GT/s.
- xxv710 in the Oculink adapter agter reseating all connections: still cursed and doesn't work

There are no suspicious scratches or discolorations on the PCIe contacts. Do I have a fake card?

Edit: Card runs at 8GT/s when installed in a PCIe slot in another computer. It really doesn't like the motherboard (plot twist: It's AMD. Works fine with Intel)