I am having some odd USB issues with my DZ68BC mobo. This is all on a very recently built home-grown PC (Win7 64-bit Home Premium, 16GB G.Skill, i2700).
It *seems* like the USB2 ports on the back I/O panel are acting flaky.
I have a Belkin 4-port USB (powered) extension hub plugged into a USB2 port on the back panel - in one of those ports is an SD card reader. Yesterday I tried copying a small 70MB file from the SD card to my HDD, and it was taking *FOREVER*. Finally, I got tired of waiting and pulled the card reader from the Hub and plugged it a USB2 port on my case's front panel (which is plugged into a mobo USB2 header). In the front panel port, everything worked great and the file copied instantly.
I have an external ioSafe drive plugged into a USB2 port on the back panel (again, it has its own power). The other day the drive just mysteriously disappeared from Windows. I cursed at Windows and rebooted, but that fix the problem. I power-cycling the external drive, and it showed up again and everything was fine. I thought it was odd, but didn't think too much more about it.
Last night, my nightly backup to the external drive started failing with Windows "semaphore timeout period" errors, which Google searches say happens when the drive isn't responding for some reason. This time, the drive still appeared in Windows, but any attempt to navigate just hangs. At this point, I started to get suspicious....
It seems unlikely it's an issue with my devices - both the card reader and external drive have worked fine for years on my old computer. Plus, the card reader works fine in the front panel USB port, just not the rear. These devices were seemingly OK a few days ago on my current PC, and AFAIK nothing has changed.
Now, I do have other USB2 devices connected (keyboard, mouse) to the back panel, and they *seem* to be OK - I haven't noticed anything, at least.
But the common thread with the failure seems to be they are both devices connected to back IO panel USB2 ports. Maybe the fact that they are storage devices (external drive and SD card) has something to do with it?
I've updated my mobo BIOS to the current version, and I've used the Intel Driver Utility to ensure my drivers are all up-to-date.