New iMac making strange sound.
Hello, I just picked up my new 27" iMac from the store last weekend and it has been doing great until today. I noticed a strange noise coming from the back of the computer. It is a loud "tick-tick-tick-tick" sort of noise that almost sounds like something is vibrating within the computer. It is a metallic sort of noise and is not anything like the occasional "click" given off by a Macbook (I have one and know the sound well). This sound is constant and doesn't stop.
Any advice or help would be greatly appreciated!
iMac, OS X Mavericks (10.9.1)