Well after much debate with my new 27 i7 and the noise of the HDD I decided to return for new one from Apple. I don't know what they've done in the space of 3 weeks but the new machine is silent. The last one you could hear the fans etc, but this new one is dead silent even when reading from the HDD. The fan speeds are exactly the same. Anyone else seen this on a RMA'ed iMac?