The fan on my PNY 9800gt wont go above 25%. I used rivatuner and fixed the speed to 60% and applied to windows startup. and that worked until I rebooted. After reboot it wasnt the same.. I cant keep the fan speed above 25% because it just goes back to 25% on its own after a few minutes, usually when I start a game.
and on topic, graphics cards are tested at 100 degrees celcius so i doubt you are running into any heat problems. 25% should be fine but run a game for a while and open up rivatuner monitor and look at you temps. 55-75 C is totally fine.