Hi, Ok im gonna keep this kinda short. A few months back I ordered a 21.5" iMac which suffered from the yellowing screen issue. I went through 4 replacements all of which had the same issue, ending in a refund and giving up. Last month I decided to order the 27" i7. All seemed fine with the machine until a few days in white lines appeared on the screen and it kept crashing. Here is a pic: So I was issued a replacement. On opening the replacement the lcd screen wasn't fixed properly inside and that had to be returned. I decided to go to a retail store to check the machine before I purchased. On opening the first one there was a unidentified black spot in the screen, not a dead pixel. The tech guy had a look and said he had no idea what it was, so they swapped again. All look fine and I went home. On firing it up at home it make the most loud ticking noise that after speaking to the apple team they couldn't diagnose, this also had to be returned. Video of the noise: http://www.youtube.com/watch?v=OqOHjFkL_NY The store done checks on another one before I collected and this is the machine I have now. So it's obvious Apple has some serious quality control issues, but thats not why im here now. My machine at the mo looks fine, the screen is fine, and so far no crashes. Im just a little concerned about what level of noise this thing should be making. Now don't get me wrong it's not as bad as the other one I had and the noise im experiencing now isn't a hard drive (i don't think) when it's seeking it seems fairly quiet, it's more of a power/fan sound not a buzzing just kind of a dull whirring/ticking. Is this normal? Can anyone with a similar machine out there let me know what level of noise they are getting? Maybe im just paranoid now, but I want to know im not getting bad systems here. I look forward to your replies. Thanks.