Hello,
I have just purchased a GA-Z68X-UD7-B3 and the story goes like this:
Fisrt boot:
-Freezes for a few seconds more than normal after award bios logo...
-Detecting drives
-ACHI Info ech. and then goes for windows load
-There, It freezes for 60+ sec in Windows logo and then loading windows normaly.
After some investigation, by disabling everything from bios including usb controllers, It worked. no freezes, windows loading in lighting speed with my vertex3.
After that I re-enabled everything from bios and unpluged all my usb devices. Worked again, everything fine.
At last: Found that the device is causing freezes is my external WD usb2.0 HDD. every time I plug it, I have this problem.
Is my HDD's fault? No, in all other PCs i tested it, works fine.
I tried to plug another portable mini hdd, when I pluged it, it worked, after some time, my keyboard became unstable and the button lights (razer lycosa) flashing. Never had this issue again. My usb devices tested in both usb 2.0 and 3.0 ports and with legacy support enabled. Same resaults.
Conclusion
Something doesnt work well in the usb controllers. otherwise, my system is rock solid. I like this mobo but please help or report for a future bios update.
Hope it isnt hardware problem that needs to replace my mobo.