When playing Killing Floor or Lead and Gold my HIS HD 3850(99% sure that's causing the noise as prior to installing it I had no such issue) makes a high-ish pitched whirring noise that will vary in volume depending what screen im in (i.e. flicking through the settings screen etc) and goes completely when I alt - tab to the desktop.
I just tried Battlefield 2 (which is older compared to KF and L&G) and there was no such noise.
It isn't the fan as I have been working on reducing the temps this evening and am well aware of how my fan sounds over 80%. Is it a particular function taking place that (on newer game) is causing my card grief?
I've been stress testing my GPU this evening and it has been running fine so why when I even sit at the menus of KF and L&G does my card make this noise? - I haven't OC'd the card btw.
So, this is happened only in 1 game?
If the other games are fine then you have a problem on the game itself...
try re-install the game or update (patch) it...
It's happened on two games but just in the menus. Killing floors main menu has some images on it and it makes the noise but so does battlefield 2 and its silent...
However the noise (whirring /electrical) is most prominent on Lead and Gold on the press enter screen...a black screen with press enter in the centre. Kf and L and G are based on other engines and probably aren't as graphically sound as say, an EA produced game but its still not usual!
check to see if any of the capacitors on the card are starting to pop, of is any of the little tiny square capacitors are broken off, that can sometimes cause a high pitched noise.
i figured this out after using a 7800gtx that got damaged from shipping.
I'll have a check today. Is the solution to RMA it in that case?