[motoboi]

Hypothesis: it’s not the CPU, it’s the USB controller saturating the thermal mass.

So instead of the CPU or GPU going bonkers, the body gets too hot and they lose thermal dissipation capacity for the normal usage and then overheat and then throttle. They go 100% on the graphs because the throttling reduces frequencies and then load becomes too heavy.

Experiment other adapters and monitors.

[scarecrowbob]

Switching which side I charge my 2019 mbp i9 effectively solved my throttling issues, so your premise might be correct as I understand it.

[Coeur]

That's interesting, could you tell me more? Like which side and port (front/back) was throttling, which side and port was not? Were you using a power supply to charge or was the mbp connected to a display? Did it only throttle during charging or also during while fully charged? Thanks!

[scarecrowbob]

According to a response elsewhere on this thread, it's not an unknown problem and there are links to more specific answers than I care to write. But to answer your question, it throttled with either left-side thunderbolt ports, with nothing else plugged into the machine using the Apple-supplied charger. I cannot remember if this issue stopped when the device battery was at 100%.

[deinonychus]

I'm not sure if I entirely understand your hypothesis, but I don't think it's 100% on the hardware - I don't think it's due to the hardware of the hardware.

I also have an M2 Air and a few things seem to consistently make my machine get hot and chug and dump the battery. Idling with my machine plugged into my 4k 144hz monitor isn't an issue, but going on a Zoom call or having one too many video streams open while docked to the monitor will do it.

Is my USB controller doing more "work" when I have a video stream open? I don't think so.

[motoboi]

In that case, zoom is transcoding video, which is a pretty damn heavy operation (note that this is why previous MacBooks didnt have 1080p webcams: they wouldn’t stand more than 5minutes on zoom without throttling).

My point here is that it’s not that the CPU (or the SOC to be exact) cannot handle such loads. It just that it cannot handle it when you have the device connected via USB-C and charging via USB-C too. Also, if using cheap usb-c to display port or adapters.

The corollary of this is that if that would even be possible, were your display wireless, or if you were generating frames by saving them on the disk, the CPU would not throttle.

Of-course that is of little utility here because the end result is the same: CPU gets slow, be it because of CPU, GPU or whatever.

[AceJohnny2]

> the body gets too hot and they lose thermal dissipation capacity for the normal usage

aka "thermal soaking"