After the v8, both of my r9 280x have died. Be carefull.
I don't really believe in coincidences... But I'm not sure. Maybe usage went up, and so did temps? Maybe they got hot enough to melt the solder, or something like that. I have a pretty aggressive fan curve on afterburner, even though my cards stay fairly cool. Around 75% fan at all times, or more if temps go anywhere over 80C.
I had same problem, it is thermopaste problem, i changed it and the problem was gone. temp went about 20C down.