Yeah, that is an unfortunate but common problem with AMD chipsets, especially on home brewed platforms. There are countless posts in these forums from members with nearly the identical problem.
You have two options, IMHO. Check to see of there is a firmware update for the computer. This probably depends a lot on which chipset that you have. I think the issue is more of a electronic hardware problem than a firmware issue.
Or, buy an active USB port expander. A passive one will not work, not even with an Intel chipset. The active expander isolates the camera from the [apparent ground loop with the] motherboard.
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