I finally got my 27" iMac (Late 2012, 3.2GHz, 8GB, 1TB, GTX 675MX) a few days ago (last thursday), and yesterday I noticed a crackling sound from the lower left corner, near the power on button (somewhere between the HDD and the bottom edge of the Mac). This crackling sound starts right after the boot logo shows up and continues to do so regularly every 1-2 minutes no matter what I do on the Mac. I thought that this is maybe the left speaker (?) but the crackling sound is still present if I plug in a headphone. I think it's not the hard drive which is the Wester Digital 1TB one, because HDD failure clicking sound is familiaar to me. So I though it could be the power supply? If I'm seeing correctly on the teardown pictures, the power supply is located somewhere in the lower-left part of the 27" iMac? I recorded the crackling sound with my iPhone: https://dl.dropbox.com/u/22655642/crackling.m4a You can here it approximately after 5 seconds. I run Apple Hardware Test and no problems were found. What do you guys think?