Scratching sound from video card

[wraith3k]

In this rig I've got a 2 year old BFG 6800GT card (agp). In some 3d games the card or some part of it emits a scratching/squeaking sound. It comes and goes as it depends on what's happening in the game at the moment. Doesn't happen anywhere outside of the game though. I know it's not from any of the fans, including the ones on the card. It's definitely not from the speakers but from the computer itself. This is also the second 6800gt card I've had (both BFG) and they've both done this. I've heard that capacitors can emit an audible sound, could this be what's happening?

 

[ProviaFan]

I never game so I don't know if it happens in 3D applications, but my passively cooled Gigabyte Geforce 6600 emits a sort of high-frequency "chirping" sound that is somewhat reproducible by scrolling quickly through light-on-dark web pages or sometimes by moving windows around.