I like many others have always been totally confused by varying reports of "fan noise" from the same GFX Cards and I think I have the answer 
Given that all modern cards with fan control are silent at idle we won't even consider that.
light-medium loads will cause the Fan to speed up (this is where the problem is)
Some fan motors will start to "WHINE " a nasty cutting sound which may or may not reduce when the fan speed increases further.
Another exact same card exhibits none of this "WHINE" and the fan speeds up to a gentle "Wooshing " sound as the air blows through the cooler !
At higher speeds I don't think people have a problem with loud Woosh, it's the "Jet type Whine" that is the problem
I would also not be surprised if some reports of "capacitor squeal" (really coil whine) are not being confused with this !
Now can we fix it and what causes it ?
basically NO, It's either the Fan motor or the PWM controller making the fan motor "Sing"....We have all used electronic speed controlled Drills, yes ?
What I would say is it seems to be much more an ATI problem than Nvidia
Given that all modern cards with fan control are silent at idle we won't even consider that.
light-medium loads will cause the Fan to speed up (this is where the problem is)
Some fan motors will start to "WHINE " a nasty cutting sound which may or may not reduce when the fan speed increases further.
Another exact same card exhibits none of this "WHINE" and the fan speeds up to a gentle "Wooshing " sound as the air blows through the cooler !
At higher speeds I don't think people have a problem with loud Woosh, it's the "Jet type Whine" that is the problem
I would also not be surprised if some reports of "capacitor squeal" (really coil whine) are not being confused with this !
Now can we fix it and what causes it ?
basically NO, It's either the Fan motor or the PWM controller making the fan motor "Sing"....We have all used electronic speed controlled Drills, yes ?
What I would say is it seems to be much more an ATI problem than Nvidia
Yeah I remember That, It was a dam good cooler wasted ! but it should have had a non-stick coating 