Hello! New in the iMac family, very new in this forum. My iMac is 5 months old, 21,5", 2.9GHz, 8GB 1600 MHz DDR3. Very late at night I noticed a grinding noise coming out of the iMac. It really has to be quiet around to notice it, but then the noise is audible and very annoying. It sounds more like the noise of a PC when something is recorded on its had drive rather the fan - I am almost certain it is not the fan. As it is so new, is it worth taking it to the service? I mean, if you think the noise is normal, I 'd prefer not to take it to the service with all the risks of scratching etc. I wonder, shouldn't the iMac be totally quiet? Thanks for the advice!