I also asked the same question on tom'shardware forums.
I have sapphire r7 260x 2gb
the thing is..
The rpm on my gpu fan, won't change. even if i set it to 10%,20%,30%,40% etc.. it will only change if i set the fan speed to 80% and above..
YES, i installed the latest driver, and YES i also tried it on the catalyst driver.. YES i used msi afterburner, YES, i also used speedfan..
but still.. i am having this problem.. please halp? is this even normal? only 100+ RPM @ 10%, 30%, 70%? cant reach 1000rpm?
here is the latest results: