It could be the fan. I have a PS4 1200 series that makes a high pitch whine when the fan is running at really low RPM's and it's intermittent. When the fan picks up just a little bit, it goes dead silent, and when it picks up a little more, I start to hear the lower deeper 'whoosh' sound instead. This didn't start until a month, maybe two after I bought it. My buddy has the same PS4 and his does the same thing, but his whine is more quiet and less high pitched. I've put my ear right up to the fan before as it's speeding up and down and I only ever hear the whine when the fan is at really low RPM's. I've seen other online forums with 1200 owners that some have this issue as well, and many have taken theirs back, only to end up with the same thing if it's the same model.
I recently set up my PS4 so it's standing up now, and it's basically fixed the problem. The whine still shows up ever so slightly from time to time, but it's minuscule now. Makes me wonder if it has to do with the fan orientation/bearings/lubrication.
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