Hi everyone, How quiet should the new 27" iMac's be running? Mine is fairly quiet but not silent. I recall reading a review prior to buying that had said it runs silent, so I'd like to make sure I don't have a defective system. I can hearing a very slight persistent sound. It's so slight I don't know how to describe it accurately--sounds like it could be a bit like a buzzing or a rotating sound. Or perhaps it's just normal operational sound? The HD will also make some sounds like it's reading something even when I'm not really doing anything. Is that normal? Thank you.