Welcome to the forums.  Since that card is the ACX cooler version, it will depend more on what computer case and case fan arrangement you have.  That cooler is more sensitive to these two items moreso than the reference blower cooler which will vent the heat out the back of the case.  The ACX cooler will vent the hot air into the case and rely on the case fans to exhaust this hot air.  What case and fan arrangement do you have?
 
Temperatures will also depend on what games you will play.  If you are playing a very demanding game, the temps could easily be 70-80C.  If you are playing a game that is not very graphically intensive, you may see temps around 60-70C.
 
Lastly, your temps will depend on what your ambient temps are.  If your room (or wherever your computer is) is hot like 30C, your temps will be hotter than if the room is 25C.  There is lots of variable that can affect the temps, so having a clear definite answer is difficult to determine.  Hope this helps.

Martin1972
Thank you very much !
My case is an  Antec nine hundred two
 
Apparently the VGA BIOS , " Keep "  The  Power settings for VGA Core and the VGA Fan Coolers are regulated to maintain 80-81 degrees Maximum .
I guess is a normal situation for the VGA. 
 
But I will  increase the RPMs of Fans case
 
Thanks for your advice !
 

 

Yes, that is correct. The GPU boost will only allow the GPU to overclock itself if two criteria are met; 1) power target is not met 2) Temp target is not met (and I guess a third one would be if the task even needs a boost or not.) If both are in the green, then it will boost up until one of the two are met. The best thing to do with these GPU's with Boost 2.0 is to keep temps as low as possible so it is allowed to overclock to its power target without having to throttle due to temps. Increasing case fan RPMs could help, but setting a more aggressive fan curve on the GPU through precision will work much better and give you better results and lower temps.