I have slight screen brightness hum when i turn it down, slight top left in the back hiss when things get really hot. I see people returning 3 or 4 iMacs for these problems. ...I just let it go. If I have music or a TV on, I can't hear it at all. Enjoy your mac. Turn the music on. I sense buyer's remorse on this item for a lot of people. ENjoy your purchase. Nothing is perfect. Stop being ULTRA picky. It does not affect performance. If you nit pick every electronic purchase you make, then you won't enjoy anything. If you stare from 2 inches from the screen and look for 1 stuck pixel, you will never enjoy your purchase. The internet has a lot to do with this. Did you ever read a review on an item on Amazon? You click on reviews. You see a TV with a 4 1/2 star average rating. Whats the first thing people do? Search for the lowest rated first. One person mentions a problem that you would have never thought to look for. You buy the product and you look for the problem described in the 1 review. You find the problem (even though you normally would not have ever looked for it) and you return the tv. I found myself returning TV after TV a few years back due to poor geometry, slight slight slight lines in the upper left corners, buzzing from the back. You know what? I never had a tv I was happy with. Just enjoy your purchase. If something doesn't work, by all means return it. But if its an issue that in no way affects performance, then just enjoy it. Nowhere in advertisement does Apple advertise a silent computer.