GPU Fan

I have a Ati hd 5670 with idle temp at 60 at 50% fan speed. when i reduce the fan speed to 30%, the idle temp is 50 and when i make fan speed to 100%, the idle temp goes down to 40-42%.
Could someone tell, what does this fan speed mean and what happens by altering it. Should i lower it or increase it while playing games n stuff.
Answer #1
The fan speed will increase automatically as the gpu temp increases.
You should not need to mess with it at all.
Answer #2
the idle temp is 50
load temp is the important one
if that stays under 60-65 you are OK
The fan speed will increase automatically as the gpu temp increases.
this should be happening when it’s under a load