Why does my HD4870 whine when under load?

[TheRedZealot]

If i get steam messages the card whines as they pop up at the bottom of the screen and when under load from Furmark or ATItool it whines, does everyone's do this?

 

[rikesh]

its the fan speed increasing to compensate for the rise in heat
if its a sapphire card it definately is this

 

[titaniumx3]

Don't forget the screaming you get when it's getting mega fps (like in menus and what not).

 

[HamZaDaG]

Happens to me with my 4870x2 (Sapphire) on the Crysis intro videos. Someone made a thread about it a couple days ago, I just turned my gpu fan up to 45% and I can no longer hear it (but this might be because the fan is so loud )