[SOLVED] What is this low pitched buzzing/short circuit sound coming from my power supply

[Hallahawk665]

Today when I turned on my PC I heard a low pitched buzzing/short circuit sound that started as soon as I turned it on and lasted for about 10-15 seconds. It sounded pretty much just like a fly buzzing against a window.
The PC continued to work fine but then about 15 minutes later I heard the exact same noise again. It lasted for about 15 seconds again and this time I went next to the pc and it seemed to be coming from the power supply. It still continued to work fine though.
If anyone could let me know what this noise is, I would really appreciate it. I never heard it before so yeah.

 

[scout_03]

use occt and stress test psu note voltages before and on test see is sound comes when on load .