Comment 50 for bug 370173

Charley -

I suggest you check the thinkpad-acpi source. I just did. There is NO automatic fan control in there. When you set "auto" it is simply setting the hardware to regulate the fans automatically. This is the default setting for thinkpad-acpi and the default setting when the machine turns on before any OS drivers come into play. The file is in git under drivers/platform/x86/thinkpad-acpi.c. The fan part isn't much code at all.

There is actually quite a bit of interesting stuff in the source. For one it says that the hardware controller will only set a maximum of fan level 6 and that 7 is only used for "thermal emergencies". Level 6 on my machine corresponds to ~3000rpm... which is basically where it sits all the time. This means the hardware controller is basically sitting at max cooling all the time. Is it possible that there is a windows driver that preemptively "disengages" the automatic control to kick up the fan during heavy GPU/CPU usage? Since the machine runs extremely hot and the automatic fan controller is at its max speed, I don't see any other way the machine would run cooler under similar loading.

Regardless of this though since nothing about the fan control has changed, if this is a truly new issue it must be related to changes in CPU or GPU power management.

James