Did you change the GPU Fan Curve ? The stock fan curve doesn't push the fan to spin at 100% unless it reaches 85c.
Apparently, for a CPU that might be a high temperature but for GPUs that's very common. GPUs tend to run a lot hotter than CPUs.
If I were you, I wouldn't worry about temps unless it stays at 80c and above for a very long duration.
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On a side note : I have GTX1060 with Dual Fans. The things idles at 38-39c and hits 67-68c under very heavy load, despite the fact that fan hits 100% at 60c and there is lots of air inside the cabinet.
If I keep default fan curve then it'll hit 70's quite often.