Reference cards working with 80-86 and living 2...3...4 years and more. Your temperature is not critical and must not damage your gpu. I have palit dual fan 1060 3g - working with 77° with 100% tdp - didn't see any problems, gpu forking fine.
Yeah I just test that, let it run 24 hour non-stop mining lbry and never exceeded 77 degree celsius so I think it's ok.
Well this was a question I wanna ask anyway, how much is the life span of a card when mining at stock settings, no under volt or over clock done by me ? If it's 2 year I am happy with that amount of time.
It is fine, but your aim should be a little lower, try to keep the card around the 70. Overclocking will not damage the card, large temperatures and frequent temperature changes from cold to hot, will. Also the life of the card should be higher than two years even at 24/7. Just check the fans, they may need a change after years of going non-stop.