Seasonic S12 - slow pulsing noise?

[caff]

Hi,

I've built this very quiet rig - the biggest problem is the PSU (Seasonic S12 500W)

It has this regular, quite bass-y humming pulse noise that comes and goes - it takes about 90 seconds to go from silent to the peak of the hum - then slowly back to silence again.

It almost sounds like a noisy DVD drive spinning at full speed... but slightly muffled - any ideas?

 

[psumann]

Try adding more load to see if that helps. If it doesn't, then you should probably RMA it.

 

[caff]

Hmm well its not the PSU! Swapped out with another one and it did the same thing - I think it's the case, some sort of resonating frequency. I tightened up all the screws and its seems a bit better now.