Question PSU Squeal Only When System Is Off And PSU Power Switch Is On

[MrThankUvryMuch]

Hello,

I recently built another PC for light gaming and schoolwork tasks. For power, I purchased a Seasonic S12 III 450W PSU. I've had a really good experience with Seasonic in the past, so I stuck with them. It seems to have an issue though. Only when the PC is off and the PSU's power switch is on, it will squeal almost like this guy's does in this video:

View: https://youtu.be/LCioIT82X4E


I'm assuming I'll need to RMA the PSU, but I'm also curious as to what causes this particular sound. Thanks!

Specs:
https://pcpartpicker.com/list/w8TJvn

 

[jimmysmitty]

Sounds like possible coil whine but seems way too loud for a Seasonic. I would contact them and look into an RMA. None of my PSUs I have ever had have that loud of a sound.