Crackling sound coming from iMac 27" (Audio Clip)

[mackry]

Hi there. 3 days ago I started hearing this crackling, electric sound coming from the top left (where the vent is so not sure if it's originating there) of my 2011 iMac 27". The crackling only starts when I am actively doing something on it such as moving the mouse or scrolling on a web page.

Here's a sound clip when I was scrolling up an down on MacRumors: http://soundcloud.com/mackry/crackling-from-imac

I've tried doing a verify/repair disk with the disk utility and tried not using a power surge protector to no avail.

Before I take it in to Apple for repair, I wanted to see if anyone might know what may be the issue. Any ideas?

Thanks,
Ryan

 

[Macman45]

That sounds like a fan with a faulty bearing in it...Revs up under load which is why you only hear it when you are working. There is a small possibility it's HDD activity, but I'm going with the fan. I'd be inclined to let Apple take a look..It's a simple enough job for them, but I don't recommend you take your 27" apart yourself