iMac noise?

Just a quick question,

I just picked up an iMac 27" 2 days and I am noticing a slight buzzing noise coming from the back of the computer. You can't hear the noise infront of the computer only when your head is behind it, the noise sounds like a fan only reason I say that is because the noise is coming from the top of the computer where the ventilation line is on the back.

Is this noise normal or should I take it back to bestbuy?

I love this mac BTW, it's my first mac and WOW hands down 10x better and faster than PC

Any help and advice is appreciated
Thanks,
Jon

There are three fans in an iMac: One for the CPU, hard drive, and optical drive. While there will always be a very slight swishing sound coming from the top exhaust vents, there should be nothing resembling a buzzing sound.

The buzzing may either be a fan, hard drive, or it could be the power supply. I would take it back to Best Buy and get another as long as you're within the 14 days to return it.