Hi. I have used three different 7970 cards since I bought mine in January through a local in-store replacement program, and all three were suffering from the same issue. The cards' performance is fine, however all three cards emitted a very high pitched squeal like noise, especially when the card is under a load and outputing a very high FPS (like at a menu screen). This is very annoying and it was present on all three cards, the first two being returned for exactly this reason, and the third card, despite being the newest, is actually the loudest of them all. It is driving me crazy. I can't stand it anymore.
I ask, is this a common thing with the 7970, or am I just unlucky? Is there some other issue that might be causing it? I know a few other people with 7970s who report the same issue.
You're describing coil whine, and it happens with all graphics cards, to varying degrees. It's also an issue with power supplies, so you might want to try verifying the source of the noise before trying any more swaps.
Other than choosing a manufacturer that opts for higher quality components, there's not much you can do, from a hardware standpoint.
At the other end, you could always turn on vsync, which will prevent your graphics card from rendering hundreds of frames per second that you'll never see.
This forum is full of such threads. It's like me, on CRT and rear projection TV's I can hear a very high pitched whine from the electron gun. You're just more sensitive to it than other people, so get yourself a good set of speakers or headphones, or just crank up your case fans, it'll drown it out.