Hi, I received this yesterday. All was well and thought great, it's dead quiet but then after I turn my PC off it starts to give of a high pitched whine. After I turn of the power switch or unplug it the sound fades over about 15 seconds.
I left it plugged in over night to see if it might just take a long time to fade but alas this morning it's still making a high pitched whining noise.
I don't think it happens while it's on unless the fan masks the noise.

I didn't find many results from google search but I did find a user review saying

I have purchased two of these in last 3 weeks and they both have a high pitch whine, the second one whined at a slightly lower pitch. Clearly audible with head near to PC and just audible over the other side of a quite room.
The whine is only noticeable when the PC is shut down and remains indefinitely unless it is switched off from the plug socket.
It wouldn't surprise me at all if they all do this but people are unaware.

I don't want to be a hassle with returns but I don't find it acceptable or something I can put up with. Are there any tests I could run or you could do on your end?

What are your suggestions.
Thank you very much.