I had this on 2 machines now: After a successful build on an OSX 10.10.3/GA-Z97X-UD5H/i7-4790/32GB DDRIII/GTX970, I get Freezes of the system when a usb device is connected (except KB and mouse). Its random and can happen after 1, or 30 min. All the components are working fine - sound, the 2 Network cards, the GTX970 (via nVidia WebInstall). I tried all combinations possible on the BIOS (F8), but still get these Freezes.. This also happen in 10.10.2.. Any ideas here?