I keep hearing this sound from my power supply. The weird thing is that it goes away when it's under load (such as when playing a GPU or CPU intensive game) but it gets pretty damn loud when the PC is idling or doing simple tasks. It sounds alot like a short circuit sound but the PC has been working just fine so I have no idea what is happening. The PSU in question is a Seasonic S12III 650W. Here is a video of the sound (you may need to turn up your volume):
View: https://www.youtube.com/watch?v=m3EmeGkOMNs