Re: UD5H and USB 3.0 issues....
FWIW with my Coolmaster 690II case and my Gigabyte Z77 D3H board (F15 BIOS) I find that this happens...
The front USB 3 ports will work all day long with both USB 2 and USB 3 sticks. No problems.
My Samsung 1TB USB 3 external HD will work great when connected to the rear ports.
The above drive is not recognised when connected to one of the ports and will disappear when connected to the other but only disappear when transferring very large files.
I have another Samsung 1TB USB 2 external HD and that will work fine off the USB 2 or 3 ports.
It has been the same for each of the BIOS updates and the drivers are the latest.
I now have a USB 3 lead connected to one of my rear ports just hanging on top of the case to connect the USB 3 drive to.
As noted my USB 3 64GB Stick will work all day long on the front USB 3 ports.
Gigabyte DS3H Z77 board (being repaired) GA-Z77X-UD5H. 3570k CPU. 2x4GB Corsair LP DDR3 memory. Asus GTX 670 2GB GPU.