Intel 82576 NIC works in top PCIE slot, but not bottom

[pfa]

Hi all,

 

I'm trying to passthrough Intel 82576EB Quad NIC to the pfSense VM and strange things are happening.

My configuration is:

AMD Ryzen 2600

Asrock X570M Pro4 MB (latest BIOS)

2x8GB Kingston 2666 some-ECC-RAM

 

MB has 2 full-size PCIE slots, and NIC is recognized by the Unraid only in the top one (the one meant to be used by GPU). If installed in the bottom slot, there are no signs of it anywhere (lspci, dmesg, etc.), though the radiators on NIC get warm, suggesting it is at least powered. I RMA'd board and replaced it with the same one - with the exact same symptoms.

It's not a dealbreaker for me, as I don't need GPU anyways (and it works if bottom slot if I ever decide to install one), but I'd really like to get to the bottom of it, as I'm scared of unexplainable stuff happening with my precious file heap.

 

Both lspcis attached.

lspci-top-slot.txt lspci-bottom-slot.txt

[JorgeB]

If the NIC is not detected it suggests a hardware issue, possibly just a compatibility problem, not much you can do on the Unraid side.

[pfa]

Interesting thing is - it's not the issue with MB, because exact same thing is happening with the replacement board; it's hardly issue with NIC itself, because it works fine in other PCIE slot (and it also works in all slots on Windows machine with different MB).

[JorgeB]

1 minute ago, pfa said:

it's not the issue with MB, because exact same thing is happening with the replacement board;

 

1 hour ago, JorgeB said:

possibly just a compatibility problem

 

[UNOPARATOR]

According to your CPU & MB combination, ASRock's specifications (#Slots) shows:

Quote

AMD Ryzen series CPUs (Pinnacle Ridge)
- 2 x PCI Express 3.0 x16 Slots (PCIE1/PCIE3: single at x16 (PCIE1); dual at x16 (PCIE1) / x4 (PCIE3))*

Without knowing the exact "Intel 82576EB Quad NIC" card, the PCI Express 3.0 x4 slot (which PCIE3 works instead of x16 when PCIE1 is also populated) is inadequate for the initialization of the card (or something like that).

Normally (especially graphics) cards would/should work with lower bandwidth slots as long as it fits the slot. (For example, I've used a PCIE x16 card with a riser connected to a PCIE x1 slot on the MB - actually in 2 completely different setups - and it worked just fine.)

Edited December 13, 2020 by UNOPARATOR
added ASRock's MB Specs link