980ti overheating issue...

I have acquired a gaming PC. It has a 980ti graphics card. When I'm on rust for example if my curve is set to Auto after 15 mins playing the temp will reach to 92°c within only 15 minutes play time. If I set the fan to 100% speed there is no overheating at all.

I know I can just put fan on full when gaming but thought the auto curve would kick the fan in?

Am I doing something wrong? Is there a way around this? The thing is my son plays it as well when I'm at work. Just would like it to be on auto and kick in so doesn't get so hot. I thought that's what auto curve did.

Any help would be much appreciated.

Thanks in advance