PSU making 'wavy' buzzing noise.

[emilhermansen]

The title says it all, it makes a wavy buzzing noise in intervals of 10 seconds between being completely silent, to buzzing very loudly at ca. 45db. Workload makes no difference, as the noise is the same intensity, but the intervals are shorter. I also tilted my case about 5° away from the main side and the buzzing almost went away. This leads me to believe that the psu is loose, and is vibrating at the resonant frequency of the case (Master Cooler CM 690 gen 1).
I just stuck a piece of plastic Lego rod thingy under one of the feet and the noise is halved. Any help would be much appreciated, thanks.

Psu: Corsair CX 550 (2008)

Specs...

Storage: 3 WD5000AAKX hdds in RAID 0)
CPU: i7 4770k
Motherboard: Sabertooth Z87 (milspec)
CPU Voltage: 1.200
CPU Bus Speed/Multiplier: 100*45x
Clock Speed: 3500Mhz stock (4500 with current overclocking)
RAM: 16GB gddr3 (2x8gb)
Cooling: Corsair Hydro Series H60
120mm Radiator (set to intake)

 

[Dark Lord of Tech]

It's most likely a CX500 if it's that old I would change it out with a newer PSU.

https://www.komplett.no/product/915831/datautstyr/pc-komponenter/stroemforsyning/enheter/corsair-tx550m-550w-psu?fromSearchOverlay=1&q=CORSAIER+550W#
Corsair TXM550W