I have been using a Z87X-D3H motherboard for some months and I had many problems with the USB ports. The main problem was the all devices connected to USB 3.0 ports would momentarily disconnect/freeze. I solved this problem using only the USB 2.0 ports (2 in the back, 2 in the front).
Recently I bought a Logitech c930e webcam, which is the one of the best webcams you can get, however when I try to record videos using the camera, the image keeps blinking (random color bars appear really quickly). I tried to use the camera in my old laptop and it worked without any problems. I also tried many different configurations, software, I even installed Windows 7 (because I'm running Windows 8.1), and the problem persists, the image will blink.
My conclusion is that this can only be a motherboard USB issue, and I would like to receive some help/input from Gigabyte.
Here you can see a Google Hangout where I demonstrated the problem...
https://www.youtube.com/watch?v=ky3L1O4FIAw
