it is a coil whine issue(if when running the computer just in windows you hear no whining then this feedback I'm giving applies, only when loads are applied will you hear harmonics). I have 40 of these cards I had purchased for a lan center and every one of them makes this coil whine. if you run 3dmark benchtest program you'll hear very high frequency harmonic hissing when the 1500fps scenes kick in. regular scenes of up to 150fps have the lower harmonic hissing coil whine. I've contacted powercolor and they are aware of the issue and notified me it is a audible only issue. no performance or life-span issues. Not sure if they would RMA your card but since I am a large purchaser, they are willing to take back every card and put a fix on them that was disclosed by AMD to manufactures.
"We apologize for the issue that you are faced with. We realize that you are a very valuable customer. Please be aware that the choke that we use is the one suggested by AMD. The solution that we have to fix the Coil Whine, is to use the adhesive (advised by amd) to reduce the coil whine..." - RMA/Tech support Dept.
However I'm still having powercolor investigate if my cards had the fix via serial number check or not since I don't want to ship back 40 cards and find out they already had the fix applied and the sound is the best it'll be. They should be able to match up the serial numbers manufacturing date and the date that they started doing the fix for all new cards and or RMA'd cards when AMD told them of the resolution.
FYI this shipment was a shipment that came directly from suppliers which had purchased a large quantity from powercolor and I received it in late February of 2014. I didn't realize the sound was not normal since I didnt use the cards in my business till 2 months ago when prepping the PCs. I'm not sure when the AMD fix came out so I am awaiting that reply as I would think my cards should have already had that fix seeing as they are fairly recently manufactured cards.
Also all my systems use corsair ax1200i psu's. So you're getting an answer from someone who's spent a lot on quality hardware and knows what they're talking about. All cards tested on multiple ax1200i psu's and professional surge protected clean power input.
I have taken a video of one of my cards for example purposes. In the video I am close to the card, however if you were to just stand infront of the motherboard/gpu area you'll hear it nearly just as loud as it is with the phone up close. If you use a case you will not hear it as much but it is still audible on high FPS scenes.
Again it is only a audible annoyance, no performance or life span issues can be correlated to the noise I am told by powercolor/AMD. Of course it is annoying still and I'd like to get rid of the sound to ensure my customers don't complain or get irritated with the buzzing if it happens during games they play that have higher FPS.
I have 6 asus directCU II 280x OC editions that are a year old and don't make a peep (i heard an extremely faint whine but my ear was literally touching the video card to hear it) during 1300-1500fps scenes or any scenes.