Not entirely true, it's the speakers which 'click', not the computer itself. My home office is in the room next to the kitchen. Since buying my Mac Pro last week I've notice interference coming through the speakers every 30 mins or so. Something which never happened with my dual 2.5 G5. I've now noticed that it happens when I hear the fridge turning itself on. As though there is a spike of electricity sent through the electrical system. My computer is attached to a surge protector unit so I'm confused why this may be happening?!