Question What's causing this high-pitched noise?

[KL4R]

Hi everyone! First post on here (hope that I'm posting in the right place haha)

I'm a noob who just finished my first 'proper' build. Everything is going fine, with the exception of the following issue....

Every time I start up/wake up my computer, the high-pitched noise that can be heard in the video I've linked is audible after about 5 minutes. After it starts, it doesn't stop/go away until I put my computer to sleep. It's a high-pitched, inconsistent noise that reminds me of the read/write sounds that hard drives make. It can be heard most loudly in the area around the CPU. I have 16 GB of RAM and one M.2 SSD and one SATA 3 SSD installed (no hard drive). It's loud enough to be audible when I'm sitting at my desk about a metre away and the case is sealed.

Bizarrely, I can hear the noise even more loudly through my headphones when I plug them into the 3.5mm jack and don't play any audio through them.

I was wondering if anyone had any ideas as to what might be causing it and what I might do to fix it. I'm worried that it's something serious that I should be looking into.

Link to video (turn volume up!):

View: https://youtu.be/uQmuyYLu6v8

 

[ACuriousMind]

Following, because my computer is making the same intermittent sound after recently adding more RAM (which doesn't make much sense). It doesn't seem related to the PSU. Not sure if it would be coil whine from the GPU, as it doesn't seem all that affected by usage. I hope you get some answers. Those high-pitched noises can be maddening.