Slot 3 Bifucation settings How?

Hi there, I have a question regarding Slot 3. As far as I understand this slot is an x8 that should be able to be used as a 4x4 with Bifurcation.

I’m already using Slot 6 with a Delock 89017, x16 to 4 x internal NVMe M.2 Card. For this I had to set IOU2 to manual 4x4x4x4 mode.

Has anyone found out how to set Slot 3 to 4x4 ??
It does not seem to autodetect the 2nd NVME as only the first one shows up.

Hello @hjboven! I’m using the Supermicro AOC-SHG3-4M2P card in Slot 3 without any issues. The auto detect in the BIOS worked just fine for me so I didn’t have to adjust anything to see all four NVME drives.

There is a big chipset on the card which is doing some switching so it might actually be running in x8 mode and doing all the bifurcation to x2x2x2x2 on the card itself. That said, the manual mentions setting slots to x4x4x4x4 so maybe it runs in x4x4 in this slot and then splits each x4 into x2x2?

https://www.supermicro.com/products/accessories/addon/AOC-SHG3-4M2P.cfm

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It does some sort of multiplexing, either two of the NVMEs though one x4 and the other two NVMEs through the other x4. Or, the note in the manual about x4x4x4x4 is a red herring and it just muxes all four NVMEs over the PCIe as x8. You could probably figure it out with some lspci commands or something. Good option to know about. As an aside, will that card physically fin in the HL8?

@hjboven you played about with the settings for IOU0 and IOU1 and those had no effect on SLOT3? The manual isn’t at all clear on how those affect which slots and I don’t have an X11SPH. If you send Supermicro a note they may be able to help confirm what is possible for Slot 3 and how to set it (Enabling PCIe Bifurcation on a Supermicro X11DPU Motherboard - Arthur Rosa - WQ6E).

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I have tried with a Startech Dual M.2 card sofar unseuccessfull. Now I have an AOC-SLG3-2M2 on order. Maybe just maybe it works with that one.

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Sadly, I didn’t check before taking my HL8 out to my brothers house to use as my offsite backup. Baer purely on memory, I think it would fit but would be tight. I think the wires from the PSU in the HL8 might be the biggest obstacle.

Thanks. Based on this image https://www.45drives.com/img/homelab/new-hl8/3-white.jpg it seems like the PSU cable might be ok (?), but the one of the front fans encroaches into the slot area of a full height card? So probably need to remove that fan and/or use the rear fan version. Supermicro says the card is 7.5", HL says the chassis is 7.93", a 15mm fan is 0.59".

Are you talking about the small fan? If so that’s a 10mm fan, but I think it’s low enough to clear the card regardless. The 120x15 fans on the front should also be low enough. Here’s a picture from my build that I think shows better that the small

No, I was mis-judging the 120mm fan height relative to the drive cage. I think it might actually fit, although any full height card there is going to be tight.

I wasn’t trying to sidetrack the thread, it’s just people have asked about NVME card options for that case/build.

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I want to bump this post up and see if someone has figured out what IOU setting it would be for SLOT 3 to split it to 4x4 without getting the Supermicro AOC-SLG3-2M2 card?
I’ve been messing around with settings for a few days and I can’t seem to get the right combination.
I’m tempted to either just get the AOC-SLG3-2M2 or a non bifurcation required card, but those are more expensive.

I don’t have an X11SPH, but here is a brief from Supermicro on setting up bifurcation on X11 systems:

My understanding from this, and looking at page 18 of the X11SPH manual, is that you would set IOU1 to x8x4x4. Note they mix zero-based indexing and one based enumeration, so it’s a bit confusing.

Thank you for the reply! That didn’t work but it did get me thinking and trying some stuff out, which aided me in getting to the solution. I also got a response from Supermicro support that I’ll share here for everybody in the future.

Each IOU option you see under the CPU Configuration generally should reflect each root block based on the block diagram. Underlined in red and yellow below:

For example, “IOU1 (II0 PCIe Br2)” should generally control the PCIe slots from root ports 2A and 2C shown in the block diagram.

With that information I first tried to change it to x8x4x4, but that didn’t work and actually gave me an error when booting saying that the Intel 40GbE 3.9.11 is unhealthy as per the picture below:

So I tried the other way, x4x4x8 and it worked! Now both drives on the expansion card are showing up and visible in TrueNAS, and no Intel 40Gbe errors on boot either!

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Hm, that seems like a documentation error with the letters. Glad you got it working.

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Thanks for finding that out, I guess I’ll revisit my Config soon :slight_smile:

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