Is USB polarity dependent?

[Caveman]

When plugging in a USB pigtail into a MoBo, the connector can go both ways... Does it matter how the pins are oriented or can it work both ways? I just built my first rig and one of the USB ports doesn't work... Maybe just flipping the connector 180 degrees would help?

 

[RSMemphis]

Yes, it does matter. The connector is typically: 1= +5V, 2= -signal, 3= +signal, 4= ground.
With my case, the front header had individual cables, so I had to figure out the exact pins. Also, it seems like some mobos are non-standard in that regard...
Don't plug anything in for long if you are not sure about the polarity. As long as nothing is plug in, you can't damage a lot, but with something plug in, you could.

Anyway, hope that helps.