Re: cpu temperature readings

[mlelstv%serpens.de@localhost (Michael van Elst)]

kre%munnari.OZ.AU@localhost (Robert Elz) writes:

>So my current guess (and it is no more than that) would be that if
>powerd happens to notice that happening, which would require it to
>look at just the right time, then powerd does a system shutdown.
>If powerd doesn't notice quickly enough, the CPU (or BIOS perhaps)
>sees that things are getting too hot, and no-one is taking any corrective
>action, and simply kills the power.

The overheating flag persists, i.e. "somewhen overheated in the past".


>I suppose it is possible that when the temp rises very rapidly, very
>quickly, as in when doing CPU intensive work, at high speed, the cooler
>also ramps up, and cools at max rate, whereas when the CPU temp just
>creeps up slowly, the cooler doesn't notice it happening, and fails to
>react - but that seems kind of unlikely to me,   It certainly doesn't
>seem like the kind of problem that can be caused by thermal paste (or
>the lack thereof).

The Cooler is much slower than the (small) die. Any rapid temperature
change is buffered by the heat sink (better if there is good
conductivity).  Air or water carry away the energy, but slowly.

I'd rather think that an idle core that is put to "turbo" speeds
is clocked higher and produces heat faster than can be buffered by
the heat sink. But if the machine is busy, none of the cores actually
reaches the extreme clock rates and there are no short term heat peaks
that trigger the "critical" flag.

That's all just guessing. But if a better connection between CPU
and heat sink helps, it might be right.