10G Ethernet via u.2>pci-e slot riser on Asus WS x570 ACE

Hardware
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Dear community,

I use the Asus WS x570-ACE in my workstation/homeserver.
All three pci-e x8 (x16) are populated (2x GPU, 1x HBA) as are both m.2 slots.

Yet I still have the U.2 available that should provide four pci-e 3.0 lanes via the chipset.

Additionally I found that there is a riser card U.2>pci-e slot available: link

Do you know if I can use this card to connect a 10G network card via the U.2 port?

Asus support wasn’t very helpful (once again). After escalating the question several support levels I got the answer that I could break out the pci-e lanes, yet “only for storage” :face_with_raised_eyebrow:

To my understanding a pci-e lane is not bound to a special type of device - but maybe I am mistaken.

I am grateful for your input on that matter

Thanks! :grinning:

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You should check manual to make sure it isn’t tied to an m.2 or some sata

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I haven’t tested the U.2 of the ASUS Pro WS X570-ACE with a riser but the PCIe 4.0 x1 slot that also comes from the X570 chipset.

I used a powered PCIe 3.0 x1 to mechanical x16 riser and this solution even worked with a Radeon VII.

The Delock riser you linked also sports a Molex power connector so I’d say you are 95 % okay to proceed.

And yes, ASUS’ support also told me that the PCIe x1 slot cannot be used for GPUs (initially tested a 75 W TDP Quadro P2000 in it, but the system would not POST since the PCIe x1 slot doesn’t supply enough power on its own).

I imagine there are similar power restrictions for an U.2 port but that should not matter if the riser has a dedicated power source.

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@mutation666 his one I have already checked. According to the manual and Asus support the pci-e lanes of the U.2 are independent.

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@aBav.Normie-Pleb Thanks! This was a very helpful answer :+1:

Did you need to set the bus speed for all devices to pci-e 3.0 as a result of using a pci-e 3.0 riser to get stability?

The funny thing is that the u.2 is specified as pci-e 3.0 only.

Any ideas if this is really the case or only due to the u.2 spec.?

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Nope, auto/default settings “just worked”.

I guess the U.2 port is only officially specified to be PCIe Gen3 since there hadn’t been any Gen4 U.2 drives to test it with when the Pro WS X570-ACE was launched last year.

For example, right now the Icy Dock ToughArmor MB720M2K-B (5.25" bay for 4 x 2,5" U.2 NVMe drives) is listed for PCIe Gen3 but the manufacturer states that it should also work with PCIe Gen4 (check FAQ, https://www.icydock.com/goods.php?id=330 ).

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Supplemental feedback: Since I’d like to also use the U.2 port for a regular PCIe AIC I think I’m getting that Delock 63952 riser, too. It seems to be the only U.2->PCIe riser available in Europe that comes from a known distributor with end-customer warranty.

If you’re not in an absolute hurry I think I could test it sometime next week (depending how long shipping is going to take) with an Intel X550-T2 PCIe 3.0 x4 AIC.

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@aBav.Normie-Pleb Cool! :+1:
I’ll happily wait for your feedback.

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The part has been ordered, will report back then.

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The Delock riser has arrived today, comes with a little medium-density fiberboard you can mount the PCB to so it doesn’t have to sit directly on the ground surface.

An AIC is sitting a little loosely in the PCIe slot but it should be okay.

Should be able to test the X550-2T network adapter tomorrow, my Pro WS X570-ACE is currently testing an 4 x 32 GB G.Skill DDR4-3600 memory kit with MemTest86 for errors which takes quite a while.

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Bad news, everyone :frowning:

The riser seems to work with PCIe lanes from the CPU only.

As soon as it is connected to the ASUS Pro WS X570-ACE’s U.2 port handled by the X570 chipset, the system won’t POST.

Also tried to enable the four U.2 Hot-Plug options in the UEFI’s Storage settings, the U.2 port also just works with U.2 NVMe SSDs, so I doubt there is a sporadic hardware defect on the motherboard.

I’m open to any ideas on how to trouble-shoot this…

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Thank you for your investigations!

Do I understand you correctly that the mainboard won’t post, even if the riser is just plugged in without anything attached?
Does the behavior depend in having the molex power connected?
(maybe it’s a problem with the electrical load and or bus termination issues)

Could you check the following:
Does it crash if you connect a m.2 nvme ssd via the adapter?
This would be the experimentum crucis if the adapter itself is defective.

Additional ideas to investigate further:
Does it hang if you set the u.2 to sata?
Does setting the pci-e to 3.0 globally have any effect?

Thank you again for all your efforts! :+1: :+1:

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  • The system won’t POST as soon as the riser itself even without the Molex connector powered or any AIC in it is connected to the X570 chipset U.2 port.

  • Using the same U.2-U.2 cable to connect the riser to PCIe lanes from CPU PCIe slots (two additional adapters used, PCIe-to-M.2 and M.2-to-U.2 just works, even with an AIC in it

  • Since I don’t have an M.2 NVMe SSD on hand I unfortunately can’t test that. I always use U.2 NVMe SSDs on Desktop systems

  • But I’ll try to populate the riser’s M.2 slot with such an M.2-to-U.2 adapter and check if I can operate an U.2 NVMe SSD with two U.2 extension cables in between

  • I’ll also try to connect the riser two the second M.2_2 slot that is getting two PCIe lanes from the X570 chipset, maybe there is something “special” with the native U.2 port I don’t know about…

  • Will also test your suggestions to force PCIe to Gen3 in the AMD PBS UEFI settings prior to connecting the riser and try the SATA mode.

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Did you get any further results?

I called the manufacturer delock in Berlin. They assured me that they too do not see any obstruction in the adapter against working with a 10G card so the behaviour is also completely dazzling to them.
They recommended trying a hot plug-in after boot with hot-plug support enabled.
If you dare to do that it could show further insight.

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Sorry, trouble-shooting my side hustle sucked up my free time these past few days.

I also thought about maybe throwing an email at ASUS’ Support but I don’t know how to bypass their first contact tech support drones to get actual UEFI engineers on it.

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@aBav.Normie-Pleb Thanks for all your efforts! :+1:

Do you have any news on the u.2>pci-e riser? :pray:

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IFF all our u.2>pci-e riser attempts fail I only see two alternative routes to get dual x8 pci-e for GPU (/ASIC) and still retain adequate I/O connectivity (HBA and 10G networking) with this board:

.) Use a m.2> pci-e riser on the secondary m.2 slot.
This should work anyhow as one of the lanes of the secondary m.2 is shared with the pci-e x1 slot.
Sure, for a 10G network card this could be a bottleneck - but better than nothing.

.) Use pci-e bifurcation to convert one of the x8 slots to two x4

According to this Asus document (LINK) bifurcation should be available on both the PCIEX16_2 and the PCIEX16_3

Has anyone tried either of these options?

Thank you all so much! :grinning:

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@aBav.Normie-Pleb

Did you do any further testing with the u.2>pci-e adapter? Any sucess? :pray:

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Honestly I forgot with all the Intel SSD drama (a few monetary units in jeopardy). I’m sorry for that!

But at least I have three soul-sucking tech support cases less than last week (Intel/AMD/Broadcom), now I can open two more (Delock/ASUS).

Will report back.

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Thank you so much! :+1:

I’ve also inquired directly at AMD D-A-CH:

They confirmed that indeed all the PCI-e lanes should be 4.0 - no 3.0 only lanes for a U.2.

Furthermore they advised to ask in the AMD forum. I’ll check that base and let you know.

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