These are perfectly normal temps. I've found that Overwatch does tend to run the gpu a bit hotter than many other games. 67-70 is about exactly the same temps I get in Overwatch with my 1080 ftw as well. The default temp limit for these cards are in the low 80's, at which point it will throttle itself more aggressively to keep from going above that temp. So unless you start getting close to that temp, I wouldn't worry about it. If the fan noise is bothering you, you can customize your fan curve using Afterburner or Precision to not ramp up as aggressively as temps increase. Though keep in mind this will make your temps higher as a result. The opposite is true as well; you could make your fan curve more aggressive to try to keep temps lower. As always though, the law of diminishing returns applies here.