Have a 2tb Samsung HDD connected as a slave to an asus p8z68-v pro/gen3. For some reason it sometimes takes 3 or 4 seconds for the slave to respond, you can hear it spinning up for a few seconds then a faint click and it works again at proper speed. Have I disabled something? After it has done this once it won't do it again until its been rebooted. It's really confusing and its only intermittent, any ideas people?