Reddit mentions of ORICO PFU3-2O2I PCI Express to USB 3.0 Host Controller Card for Mac and Windows with Dual Rear USB3.0 Host & Internal USB3.0 20 PIN Jack and Low-Profile PCI Slot Cover Plate

Buy a 3.0 -> 2.0 adapter or if your motherboard has expansion slots, buy a 3.0 add-on card like this.

I would urge you to go with the latter if you have the space. The x1 card will work in an x16 slot.

Nice find!
That was very... "entertaining" read. Sadly I already had Legacy USB disabled in UEFI setup. I am definitely going to check the mentioned usb mailing list later.

The thread also references it being used on a laptop, which throws in a sizable chunk of power management quirks and BIOS hacks, on top of it being ExpressCard device. I have PCIe x1 desktop card, but by pure luck I have same ExpressCard controller. I'll grab some spare SSD and drop Linux on my laptop later to see if issue exists there.

Just for the sake of completness I forced mentioned pcihp, but I am not going to rip out the card from my mobo

I am very, very close to abandoning this device altogether. But... you mentioned libvirtd and vfio, which happens to be my use case too, and yours works. Would you mind sharing some details? Whether the guest is linux or Windows, or does the hotplug works? In my case, the guest is also Linux, which just escalates the issue one level deeper, since power cycling the machine is a lot of hassle already.

You also dropped another gem in form of Fresco Logic - I think I recognize this company from its USB to VGA adapters, but you say they also make USB controller chips? I believe I have seen only VIA and Renesas solutions before (there's Intel too, but their design is internally based on Renesas one) What are your experiences with these?

edit: Found this one for $12, it doesn't have 19-pin internal connector, sadly, but as long as it works.

edit2: Orico makes Fresco 2+2 adapter :)

edit3: Well, Orico states Fresco is not compatible with MacOS and Linux, and suggests a SKU with VLI chip.

edit4: The ExpressCard behaves like a drunken madman, even in Windows. Like depending when I insert it to the system, it gets detected or not, throws PCIe errors or not, detects devices or not, but even if it works, it overheats quickly (i.e. when copying to USB SSD) and shuts down, disappearing until next power cycle. (including removing battery). I gave up trying to check it under Linux.