I started my new job (research post) on the 4th of January with a brand new Mac Pro which sounded like a jet air-craft so it went off to have the graphics card replaced. Yesterday it returned (i.e. after 1 1/2 weeks!) and it is nice and quiet. After less than a day's use the monitor suddenly starts blinking on and off with an associated click on the speakers. This is a 27inch Apple display (also brand new). It is intermittent but once it starts the monitor turns off for a few seconds, then on for about 10 seconds then off again for a couple of seconds and so on. It is worse on one mini-display port socket than on the other. A Dell monitor plugged in via an adapter seemed ok. I guess this means that I'll be without my computer for another couple of weeks. I went for the Apple option because I thought it would be nice and quiet and reliable - so far it has been just the opposite and makes me appreciate the boring reliability of my Dell workstation at home!