My new iMac (i5) has a quiet WD hard drive, but it has yellow on the bottom right and the high pitched noise that gets worse when the brightness is turned up. I already have a RMA on it and will get a replacement soon. I would like to know how prevalent the high pitched noise is on the 21.5" iMacs. I have seen many topics about the yellow screen, but not too many about the high pitched noise. I know some people have gotten perfect screens, but what about machines with no high pitched noise? I could live with a machine that had some slight yellow, but the noise gives me a bad headache.