The old method is to stop a fan for a short period to find which one it is. This old school method seems to be forgotten yet I still use it.
There is something resonating in my case which sounds like a fan for one day now. I installed a new case fan 2 days ago so I figured it was that fan, but it wasn't. I concluded that the following pieces are not the culprit:
Front or back case fan
Fan on GPU
Fan on CPU
The motherboard is also not loose or anything, so it can't be that.
The video below is recorded on a phone so the sound itself is way softer than it is in real life. Despite that, it still shows off this noise.
The only fan I can think of is the fan in the power supply, but as far as I know, it is not smart or even possible to turn that fan off. Testing it without the power supply is also a bit difficult, of course.
If anyone has any idea's on what this could be (besides the power supply) please let me know. It is driving me absolutely crazy!