I have the P67 E4G3 and i can say i have had problems with the Etron USB 3.0 since day 1.
Since yesterday my desktop freezes on load screen of games (start-up). The PC is totally stuck and needs to be restarted.
I installed latest Etron drivers few weeks ago because i bought a backup drive for my systems and the backup kept failing due to random disconnects of the USB device.
This problem was fixed with the latest driver and i was able to backup and use the Etron usb 3.0 without any problems.
The only obvious thing i could see in event log are these:
Detected unrecognized USB driver (\Driver\EtronXHCI).
Detected unrecognized USB driver (\Driver\pci).
Nothing is or was plugged in (usb3.0) when these warnings appeared.
I have a i7-3770 and gtx 960 with 16gb ram, nothing overclocked.