I own the Z77X-UD5H and tried to pair it with an IB and had all the lockup nightmare's you've read about. I don't buy the USB driver theory, I've had this board lock up in bios and during memtest86. It's pretty evident that it's a BIOS issue at this point and I *really* wish Gigabyte would get a...
Good luck with the Gigabyte board, mated with an Ivy Bridge they seem to have lock up and power off issues. (http://forums.tweaktown.com/gigabyte/48463-gz-z77x-ud5h-random-freezing-shutdowns.html).
Mine's been a sheer nightmare of testing EVERY component on known good systems to where it's...