schade

As of July 4th this is still an issue. Without the ''--no-auth" flag (in post-arguments not additional) it asks for username and password (of which no sane default combination seems to work; with this argument it asks you to set one but fails, as auth is disabled, but goes no further. I have deleted the entire `/mnt/user/appdata/portainer` folder and still no joy for either method.

Just as a test, try removing the usb card in slot6 and see if passthrough works properly. There are no guarantees, but with slots 1, 3, 5, and 7 in use slot 6 may be causing issues. If it doesn't work you can put it back and use SeaBIOS until we figure out a better solution.

According to the specs the cards should be in slots 1, 3, 5, and 7 to get full x16 to each. Your unRaid box (the GT210) should probably be in slot1 to function properly. Beyond that, nice motherboard; I don't think they sell it around here. I may have to change my plans for the final box I'm building after my trial.

Regardless of the fact that those 7 slots are designed as x16, only one or at most two will be used as x16, and in some slot combinations some of them may even been running at x0 (disabled); it all boils down to manufacturer specifications. Here is a list for one X99 chipset that I am familiar with but others are likely the same: Slots: 5x PCI-Express 3.0 x16 Slots (run at x16/x0/x0/x0/x0 or x16/x0/x0/x16/x0, x16/x0/x0/x8/x0 or x16/x0/x0/x16/x8, x8/x8/x0/x8/x0 or x8/x8/x0/x16/x8, x8/x8/x0/x8/x4) As you can see there are quite a lot of x0 in some of those. All that aside, if it's working for you in SeaBIOS by all means use that.

Fair Warning: I am on day 3 of my unRaid trial and using the 6.2 beta. I currently have two Nvidia cards in my unRaid server and no onboard graphics. I use the first card (Gt330 in PCIe0) for unRaid and the second (GTX750ti on PCIe2 [not PCIe1]) for my VM running 8.1 on OVMF. This has been working fine for me thus far. You might want to have a look at your motherboard specs and see if the PCIe lanes are compatible for SLI/Crossfire in your current slots as sometimes they will need to be separated further than the slots you currently have them seated in. If there is something I can do to help test out your issue I'm more than happy to oblige.