Re: [gentoo-user] Re: lm_sensors much hotter in 2.6.31 than 2.6.28

[Volker Armin Hemmann]

On Montag 26 Oktober 2009, Grant wrote:
> >> After upgrading from 2.6.28 to 2.6.31, I noticed my CPU temperatures
> >> are reported a full 20C hotter.  If I load the old kernel, the
> >> reported temperatures drops back down to normal.  Has anyone else seen
> >> this?
> >
> > If you're using coretemp as sensor, the temps are always off (the
> > coretemp sensor of Intel chips is not accurate, not by any stretch of the
> > imagination.)  It only reports the distance to the CPU's maximum thermal
> > junction, which then the coretemp driver *tries* to translate into a
> > temperature, but the result is wrong since the value reported by the CPU
> > is not accurate to start with (it only gets accurate as you approach the
> > max value).  That maximum value is totally undocumented for desktop CPUs
> > (the docs Intel provided recently are wrong.)
> >
> > You should use your mainboard's sensors instead for accurate values.
>
> I'm actually using k8temp.  Do you think it is susceptible to the same
> problems you're talking about?  I also have an ACPI sensor available
> named THRM.  Should that one be more accurate?
>
> BTW, another system of mine (Dell laptop) only seems to have available
> coretemp or an ACPI sensor which reports values like 46960 mWh.  Am I
> totally out of luck with that one?
>
> So, In the end, it's fairly impossible to monitor a CPU's actual
> temperature in order to keep it below the published maximum?
>
> - Grant
>

there are no published maximums. Ruin a good evening going through CPU specs. 

And k8temp has the same problem. Or similar. Some CPUs report correct temps, 
other doesn't and some report some complete bogonium.