I have 2 fans taking out air and the case is quite clean, airflow isn't amazing but not bad. Bottom of the card is very very lightly dusty but nothing big, I live in Sweden so no, not a hot climate. And I've had this card for maybe.. 3 years or maybe less. New when bought.That is higher than expected. Poor air flow in the case? Dirty case/card? Live in a hot climate? New card or used?
I cannot find the fan option anywhere on GPUTweak IIWouldn't by any chance happen to be running the gpu in fanless mode? That's switchable by using Asus gpuTweak2 and default is On. Turning that off will start the fans spinning along a predetermined fan curve like the cpu. Otherwise the fans don't come on until @ 65°C, at which point they will cycle on/off quite loudly. With the fanless mode, 50°C idle is very common