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I have two Studio ultras absolutely no noise from either of them. Even at high workloads ...... silent. Your "Known issue" is rubbish in my experience. Does your Studio make a noise?
It is a specific issue. It does not affect all units and would not be noticeable with even a moderate noise background. It is approx 2200hz and will drive you out of your mind in a silent environment. It can be there from day one or show up even months later. I had 2 and one had it out of the box the other showed up at around 10 days. That being said I have owned used Mac minis since PowerPC days and low cpu load the studio is louder than ANY Mac mini. Last I researched it Apple does not know how to fix it. They pull out the parts cannon.
 
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