Wierd fan noises, probably PSU

[Niqesse]

Today my PC started to make a whole lot of noise. Sounded like a fan spinning at full speed, but none I had heard before in 2 years of using this system.
I also didn't put my PC under a lot of load, just the browser and a very simple game.
I checked every single fan in my system and concluded that it's most likely the PSU.
So I monitored the Wattage and System Temps, everything seemed fine, nothing above 50°C or 40W.
Restarted my Computer because I got quite worried.
Opened it up to check all power connections and the GPU's cable wasn't properly plugged in.
I restart, thinking all is well and after 10 minutes the fan spins up again under low load. Monitored the system - still nothing out of the ordinary.
After 3-5 minutes the fan powered down.

Right now I am unsure if this is anything to worry about. My PC had had some hiccups in the last days (freezing, blackscreen probably caused by a broken clamp on the GPU's PCIe Slot.
Moved it to the lower PCIe Slot, now it's fine) but I don't think the issues are connected.

Here are my specs:
CPU: AMD Ryzen 7 5800X
RAM: 16GB @3600mHz; DDR4
Mainb.: MSI B550 A-Pro
GPU: GTX1060 6GB
PSU: Corsair RM750

Any advice is appreciated

[Sjaakie]

a video would help. RM750 should be pretty quiet. Are you sure it's not the gpu?

[Niqesse]

@Sjaakie I can upload a video as soon as it happens again. I tested if it's the GPU. Doesn't appear to be