Why is my PC making a very loud electrical bussy sound?

Hey guys, rebuilt my PC roughly 2 months ago. Since the rebuild, it makes this very loud buzzing sound that increases and decreases in volume intermittently. I've attached a video as an example of the noise at it's loudest. What is the cause? And how do I fix it?

My specs are: 9700x3D - CPU 3060Ti - GPU Corsair RM650W - power supply Corsair VENGEANCE 32GB PC5-48000 DDR5 - Ram TUF-GAMING-B650-E Wifi - motherboard