James Sweet wrote in news
8EFh.6020$RN6.3214
@trndny07:
That's a switchmode power supply....
Switchmode power supplies do not hum. (Where "hum" is defined as a 50 or
60 Hz, or 100 or 120 Hz sound.) They operate at much higher frequencies.
Which is the whole point of a switchmode power supply: higher frequency
means less iron.
Original poster: What did you hear from this power supply that got this
whole thing started? Describe the sound.