I have been an IMac owner for about 2.5 years. I do voice work for media outlets in the US. I have noticed a lot of complaints about hum on the IMac. I am currently on the 10.8.2 operating system. I have tried everything to get rid of the hum with no success. Unfortunately this hum bleeds over into my audio recording I went to the genius bar at my local Apple store and he suggested it could need a fan replacement. Or perhaps it dust. Very disappointed in this product. It's a lot of money to spend and then endure this issue. Don't get me wrong. I have apple everything in my family. But The Apple product I spent the most on has been the biggest disappointment. This iMac was produced in 2009 and I purchased it in 2010 as the PC I owned was getting old. I never hum issues with the PC. Although I not a PC fan. I can say that I never had these kinds of issues with it.