I've been having USB issues with my new DQ77MK. Wireless USB mice (I've tested three, two Microsoft and one Logitech) get jumpy during high CPU activity, and become completely unresponsive when I plug a SanDisk Extreme 16GB USB 3.0 flash drive into any USB 3.0 port (front and rear). This does not happen when I plug a USB 3.0 external hard drive (Western Digital 3TB) into the USB 3.0 port, so it appears to be specific to the SanDisk Extreme. The issue does NOT occur when I plug the SanDisk Extreme into a USB 2.0 port, OR when I use any USB 2.0 flash drive in either USB 2.0 or USB 3.0 ports. I am running the latest chipset and USB 3.0 drivers from Intel's site as of 02/13/2013.
The issue also does NOT occur when I use a wired USB mouse.