I've got a 2012 i7 that will regularly overheat. The way this manifests itself is that the machine will get extremely hot, fans will spin to max, computer will restart, then I will get the repeating three tones (which theoretically indicates a RAM issue). I can unplug the power, replug in, and the computer starts up fine. This is what I've tried: reformatting and starting fresh, changing RAM (both slots, twice), using an application to increase fan speeds. Nothing has helped. I even cloned the mac onto a 2012 i5 mini to see if it is software related, but the i5 does not exhibit the same issue. Is it a good bet, at this point, that there is an actual hardware issue and worth taking it to the Apple Store? Or am I missing something else to try? Thanks.