Short burst of buzzing noise from AX1200i

My brand new AX1200i is making a very annoying buzzing noise. The noise lasts less than a second and occurs every few seconds (sometimes in very quick succession).

The noise used to be regular, when I first noticed it I actually clocked the noise to once every 10-11 seconds, which made me suspect an air bubble in the waterloop at first. Now it's irregular and every 2-15 serconds once it starts. I know for sure that it's coming from the PSU.

It doesn't matter what the PC is doing in terms of load or other activity, the noise pattern (if it can still be called a pattern) remains the same.

I also know that it's not the fan being broken as it doesn't spin when the machine is idle... and it doesn't make any special noise when setting it at manual RPMs via Corsair link.

Small update. I tried the self-test button and all I got was a mechanical-sounding click. No light or anything. That can't be good? Never tried the self-test button before, not used to having one so I never thought about it.