PCIe-USB card stopped working

[JD1]

Hi everyone,
This seems like a problem with either BIOS, Ubuntu/Snakeoil or my SOtM PCIe-USB card but I seem to have ruled them all out so I am stuck.

I've always used SOtM PCIe-USB card to connect to my DAC. While messing with a PCIe-network card, the PCIe-USB card started having sporadic problems then stopped working completely.

With my DAC (or a USB stick connected) in the SOtM USB card, the USB device is not detected under "lsusb" (upper screen) and on startup, I get messages like the lower screen; "Unable to enumerate USB device".



So far I have tried:
BIOS: reverting to default and flashing in more recent BIOS
Snakeoil: reverting to old FW, swapping OS SSD for one with very old Snakeoil OS and running via ISO/Live CD on USB drive
PCI-USB card: Have tried 3 of them (all same model SOtM cards)
DAC & USB cable: Works fine if I plug into motherboard USB port
PCIe slots: Tried all 4 on my mobo; none work with USB card; all work with network card

Any ideas welcome.
Thanks kindly,
JD