11-08-2019, 05:54 AM
(11-07-2019, 07:14 PM)diodelass Wrote: I was noticing a bit of a whine when I was first messing with it, whenever a GPU operation took place. I can't seem to get it to happen again now, because I think I sneezed in the wrong place and made GPU acceleration stop working (thanks, silicon vendors!). In any case, this particular phenomenon is one I'm familiar with: GPUs, for whatever reason, pull a lot of power in sharp pulses. This tends to cause switched-mode power supplies to respond by ramping up their output in pulses in kind, which produces all kinds of mad EMI that sprays everywhere. On my phone, for example, I can hear little buzzy noises whenever the UI moves around while I'm listening to music in wired earbuds - and much more startlingly, I can hear these same noises coming from the wallwart power supply whenever I use it in a quiet room while it's plugged in! The fact that the power fluctuations make it that far out of the phone without being buffered away is rather concerning...
My guess is that the whine you're describing is caused by this GPU-related power flutter. If it's loud enough to be a problem, there are a few things you might try to fix it, but since it's a hardware issue, none of them are particularly easy or ideal. If it's only happening with the speakers on (were you playing sound through them from the video?), then it might just be a matter of turning the onboard speakers off and using a bluetooth speaker instead, which will avoid having the audio system amplify the whine and spew it into the audio. If it's actually coil whine coming out of the power regulator itself, and not from the speakers, then that's another matter, though in earnest I can't quite believe that any laptop power regulator could generate a whine loud enough to be a serious problem without also being at death's door, one way or another.
With luck, using a wireless speaker with its own power supply will do the trick. If not, we guess the thing to do would be to open it up, find the power rail that's most directly involved in feeding the GPU, and solder a great big buffering capacitor to it. But that sounds pretty tricky and risky.
Thanks @diodelass - I've heard of GPU coil whine before and was hoping it wasn't the cause. Will try to pinpoint the culprit component emitting the whine.