After 1 month at 4.2Ghz, it attempted the 1st stabilization of a 4k video & prompty crashed.  It wouldn't post anymore until the clockspeed was lowered to 4.1Ghz & memory was lowered to 3400Mhz.  The voltages remaned on auto.  No manual voltage tweeking improved it.  

It was the end of an era.  There probably is a short term fuse which lasts just long enough for product reviewers to hit a higher threshold & throw it away.  Like an old fashioned lightbulb, it eventually burns out.