Hello Recently, I've been hearing some strange noises form my late 2009 27" iMac. it's a ticking of sorts, it's been sporadic for the past week but today it's just been constant while the computer is idle. My gut says it's the hard drive, but from googling it could also be the PSU? If it helps, it sounds clearer when I put my ear right to the Apple logo. Here's a poor recording: http://clyp.it/qtva2lxd.mp3 I know that I was eligible for the hard drive replacement program Apple had, but I never got around to taking it in. I'm due to install an SSD in the optical drive bay next week, should I pop in a new Hard Drive while I'm at it?