I don't know how helpful this'll be, but I sort of had a similar problem with my 8RDA+ when I first got it...except it was my USB that wasn't working. After digging around AMDforums, I found some threads involving 8RDA users that had issues with IRQ sharing. In BIOS I tried disabling some things I wasn't using, specifically the onboard audio. Then the USB started working fine.

Sucks that I had to disable things to get others working, but overall it's not a biggie for me - and I'm sure there's a better solution that keeps everything working.

Good luck!