I’m curious, how many people are aware of these sounds. I have designed, etched, and built my own switching power supplies along with winding my own transformers. I am aware of the source of the noise. So, does anyone else hear these high frequency sounds regularly?
The switching frequency is usually set by a small capacitor that is on the mains auxiliary power circuit. This may degrade depending on what kind of capacitor was used. There is also a small electrolytic capacitor that smooths the auxiliary power for the chip itself. If this capacitor degrades too much, it can cause some switching frequency stability issues too.
My current laptop supply sounds about like R2D2 when my GPU is running full tilt and I’m maxed out on 18 of 20 cores with AI.
But that’s the thing it happens at idle, and I’ve tried fixing it by unplugging+discharging and letting it sit unpowered in my colder-than-average room for 5 hours or so and it was still happening when I booted back up. So time or some other random thing seems to be a bigger difference.
When I had it not happen for days, doing anything that made the fans ramp up didn’t cause it to happen (even full tilt as you said). In fact most of the time it’d start with nothing open other than the browser.
I thought it might’ve been dust (despite my PSU being the least dusty component) but after dusting it doesn’t seem to have been the issue.