My PS4 slim started making this noise shortly after putting a new power supply in it. The sound would also continue for a short period of time once I turned off the PlayStation. It worked for about 2 months with the sound then it just turned off and doesn't turn back on , but when plugged in I can still hear the sound and when I try push the on button it changes pitch. It also still makes the sound for a short period of time after unplugging it. I want to think it's the power supply but it's brand new ,original one in it and the hardrive is still the same from when it was bought in 2016 so might be the hardrive.