Whenever my GPU is performing a low-power but highly repetitive task, the coil makes a noise like a Star Trek TOS tricorder. I've read that it can be caused by a cheap PSU, but my PSU is by no means a cheap one. Does anyone know if it gets worse over time or if it just remains like that. I'd honestly never heard it before. Read my system specs in my profile and maybe you'll see something I don't. Cheers!
I have heard of this happening, but have never experienced it with my 4870, as far as I can tell. But to be fair, I am very aggressive with my case ventilation, and since my wife and I both game with headphones, any sort of noice like that might be drowned out by the constant roar of my 90cfm 120mms at full rpm.
I never heard it until I got an Antec 900(damn you open design vs sonata's rather closed design). It does not seem to get worse with time. My current card does not do it, but i have had 2 that did(X1900 and 8800GTX[boy was this one loud]). It should not hurt the card in anyway.
This is fairly common issue and there is a easy band aid solution. I did it with my x1900xt using the ram sinks of a geforce5 and on my 8800gtx had to use some cut down fins of an old cpu cooler both worked at reducing the coil squeal.