I am on my 4th iMac which is a bit ridiculous i know but each one has had an issue. 1) Crackling noise coming from bottom left of screen 2) Fan bearing causing a rattle and a dead pixel 3) Crackling again, exactly the same thing. 4) Fan rattle again and shadow / line on far left of the display. I feel disappointed at these issues and am wondering if it is just me. My wife can hear these rattling fans. They begin to rattle after about 30 mins of use. The crackling at the bottom left of the display happens mainly at low brightness 1 - 4 bars and when there is dark images dominating the screen or videos. I am assuming it is related to the power the panel consumes and/or the PSU. My wife can't hear the crackling but it is super frustrating for me. Im curious as to why i've had 2 iMacs now that crackle, what could possibly be causing this? It doesn't happen in windows on the same machine at the lowest brightness. I can live with bumping up the brightness to around 6 bars to stop the issue for reading text but this is a bit bright when i'm working late at night plus it doesn't stop the issue if i'm watching full screen youtube. I have also experienced the ticking of the tape as the machine begins to warm but this will go with time. I also find it bizarre that both machines with the fan rattle haven't had the crackle and both quiet fans have had the brightness crackle. It's like i either have to live with one or the other and i'm really surprised more people don't notice this. My room is quiet but even with background noise i can still hear it. I love Apple stuff and i love my air and rMBP but i really would like to have an iMac, so far i'm questioning whether i can live with these issues.