On Mon, Oct 26, 2009 at 2:44 PM, Grant <emailgr...@gmail.com> 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?
Hmm, the k8temp documentation seems to indicate that it should be actual temperature: "Temperatures are measured in degrees Celsius and measurement resolution is 1 degree C. It is expected that future CPU will have better resolution. The temperature is updated once a second. Valid temperatures are from -49 to 206 degrees C." Also, with lm_sensors not all sensors can be auto-detected. I had to manually specify mine (Abit uGuru3).
