Preceding this smoke was a large 3" spark excitement arcing light show, burning plastic and electronic components, my first AMD Radeon fire! Whimper, it's dead Jim.
The best hypothesis so far is that it got out of position when I recently moved and as I pressed the reset button on the case it jarred the card just enough to short circuit during power start up time when there is more current coursing through the system.
Yes, that is gray smoke you can see in the video frame. Click through to the Instagram video for the full horror.
Watch the horror of smoke coming out of a GPU: https://www.instagram.com/p/BdFLK4PhOKy.