I believe the same maximum operating temperatures of the 6000 series GPU cards are the same as the 5000 Series GPU cards.
The 6000 series seems to have two different temps, Regular or Normal and Hotspot Temps.
I believe the hotspot Maximum Operating Temperature is 110C. Which means that when one of the various Thermal sensors throughout the GPU Card reaches and passes 110C the GPU card will automatically throttle to keeps temps at or below 110C.
This is normal for the 5700 GPU card. I asked one AMD Contractor via AMD Chat and he mentioned that the 6000 series Hotspot should be kept at 110C or lower.
So if your 6800XT hotspot is at 105C it is very close to being throttled or slowed down by the GPU Card.
Also make sure the GPU fan air flow is not obstructed in any way and you do have good air circulation inside the computer case.
But if the GPU is under very heavy stress than that might just be normal temperature under that situation plus your normal/Regular Temperatures are pretty low, but just guessing at that.
