hi, im new to this forum so try to cut me some slack
i have a Nvidia 7600Gt and thats a pretty loud card, not quite good as yours

. im sure its just the noise that the card makes when it is processing what is going on, on the screen. it gets louder when playing games or even if i move a window round on the desktop. the same time i moe the window the card makes a noise. i dont think that the noise is anything to worry about