Blown fuse on USB port?

[Kjetil]

A while ago a friend was helping me to get stepper motors running off an arduino with a L298N bridge, when some of the power intended for the steppers accidentaly got routed into the USB port instead. The computer wasn't too happy about this, and instantly rebooted, but came back up without any apparent issues (and a nasty error message saying it had rebooted due to a power surge on the USB port).

The USB ports still work fine for most equipment, but they only work as USB 2.0 ports (they are USB 3.0). This is shown clearly from both the performance, and that Windows asks me to plug USB 3.0 devices into a faster port. The drivers haven't changed, and reinstalling them haven't changed this behaviour. I am also unable to run power hungry devices off two of the four ports, such as cellphone charging.

Could this be something as simple as a blown fuse or other component, or is it likely that the controller is fried? I find the last one less probable as it apparently retains most of it's functionality.

[marshallh]

If you drove a bunch of current into the superspeed pairs on the controller you probably fried the serdes in it.
This is why you always use a hub when dorking around, or an isolator.