I already set up a return, so I'm not sweating this, but I'm at a loss to what is wrong with the iMac. Opening certain apps on the iMac cause it to make a high pitch squealing noise. Not incredibly loud, but noticeable, and it's loudest near the USB ports. Unplugging a USB device and then plugging it back in briefly stops the noise, but then it continues. Some apps cause a fainter hum, and others nothing. The sound is always intermittent. This happens with devices connected or disconnected, so it's not an external hardware issue. Maybe it's the processor? Apps like Maschine cause the worst noise and are more CPU intensive. I don't think it's the SSD. Not sure what else it could be. Any ideas?