I have just taken delivery of a new 8GB i7 with SSD iMac, however it makes what I would call a buzzing sound. There is nothing coming from the speakers and adjusting the volume does nothing. Adjusting the brightness makes no difference (someone said somewhere that this could be the issue). The noise is the one that you hear when the Mac is first turned on and the noise you last hear before it is turned off. So if I sleep it, the screen goes black first, and the noise stays on until the last second when everything goes off and completely silent. I can't work out which side of the iMac it is coming from though. The problem (or I think it's a problem) is that it's permanently on, although it is quite quiet. I would say it's the same noise volume as an HDD makes (although it's not the HDD and it's constant and it doesn;t sound like a HDD, I'm just using that to explain how loud/quiet it is). Should the iMac be ultra silent, like say an iPad/iPhone/any mobile phone, or do you expect this buzzing noise permanently? Thanks in advance.