Update:

I'm sorry to say that I still haven't resolved the problem with my MX5 and coil whine. [now solved - see edit below!]

It makes no difference whether there's an Active PFC or Passive PFC power supply feeding it - it's still chirping/whistling away.

I have just noticed, though, that when I ...

Hi, Tom. Thanks for responding! :)

No, at the moment I've not connected anything to the GPO - I'm still at the "let's make sure the basic operations are okay first" stage.

More internet searching on my part has perhaps shed some light on the problem. My Sea Sonic Tornado PSU utilises Passive PFC ...

Hi, folks! :)

I've recently become the proud owner of an MX5 and am encouraged by the potential I can see in it. However, my computer appears to be less enamoured with it. :(

When the display is active and running LCDC, the PC emits a high-pitched electronic whistling/warbling noise. More ...