Unreasonably high temperatures

jsgt · 2011-10-09 07:17:26

I have a Thinkpad T60. Yesterday, I put the laptop into suspend mode and had it in a 10-15 degree Celsius room. When I turned it on again today, sensors reported the CPU is at 55 degrees Celsius. I find this unreasonable. However, if you change the units to Fahrenheit, it comes out to 12.8 C, which is reasonable. I therefore suspect lm-sensors is interpreting the CPU temperatures as Celsius when they in fact should be read as Fahrenheit. Has anyone else had this problem or does anyone have a solution?

twix · 2011-10-10 12:13:37

55 degrees Celsius is perfectly normal for a laptop, don't worry.

And 12.8°C is way too low for interior use : in your house there is probably around 20-25°C currently, so a lower temperature for your computer is impossible

jsgt · 2011-10-11 15:17:27

Thanks for your answer. I know 55 degrees Celsius is normal for a laptop, but certainly not after having slept for hours. I measured the temp less than 30 seconds after having brought the laptop out of sleep, so I find it very curious that the temp could rise more than 35 degrees in such a short time. When the laptop idles, the GPU and CPU go up to ca 75 C. Perhaps 12.8 C is a bit low, but my room temp is definitely not above 17-18 C, so maybe it's just a problem of faulty thermometers.

ewaller · 2011-10-11 15:41:44

A CPU can reach those junction temperatures very quickly. The CPU temperature is not a thermocouple or thermistor on the case or heatsink; rather they included in the design of the CPU a structure, built in the silicon, that allows them to measure the current through a a PN junction. That current is a strong function of both voltage and temperature.

R00KIE · 2011-10-11 20:44:50

But don't forget that the thermal resistance from the silicon to the heatsink can't be too high and it takes some time to get a heatsink hot, also coming out of suspend doesn't take that much time or cpu power ... unless the OP meant to say hibernation instead of suspend.

jsgt · 2011-10-27 11:59:45

Thanks for the responses. I meant suspend.

I have to underclock my CPU to about half its nominal speed to keep it from overheating. At half the clock speed, it idles at between 80 and 85 degrees C. I've cleaned off all the dust from the fan without any significant results. Can it be a software bug?

ewaller · 2011-10-27 13:31:08

jsgt wrote:

Can it be a software bug?

Anything is possible -- yes it could be a software bug.

It could also be a large thermal resistance between the heatsink and the CPU. As I have mentioned, the temp is measured inside the CPU. Many modern heatsinks do not use the nasty white heat sink compound left over from the CPU must not have gaps more than about 1 mil. This type of material cannot be reused. Often, people make the mistake of removing such a heat sink and replacing it with the white goo junk.

Have you removed the heat sink?

jsgt · 2011-10-29 11:02:28

ewaller wrote:

It could also be a large thermal resistance between the heatsink and the CPU. As I have mentioned, the temp is measured inside the CPU. Many modern heatsinks do not use the nasty white heat sink compound left over from the CPU must not have gaps more than about 1 mil. This type of material cannot be reused. Often, people make the mistake of removing such a heat sink and replacing it with the white goo junk.
Have you removed the heat sink?

I have never removed the heat sink, but perhaps the compound has degraded over time. I changed the power settings for the video card which seemed to lower the CPU temperature a bit as well.

nathan28 · 2011-11-01 15:50:06

Stupid questions first: Is your T60 with the original heatsink assembly? The fan probably needs to be replaced and the heatsink compound is def. past its service life.

I have a Thinkpad R60, which is the junior-varsity version of the T60. It's old and would run hot in XP, the Ubuntu/Mint kernel and the Arch kernel. 55C is a high-normal temp, 60-70 under heavy loads like virtualization/Dwarf Fortress or kworker drama, so I've looked into this a lot. On edit I've had only one true overheating incident where it shut down immediately and this was while running something in WINE.

My chips are the Core 2 Duo 1.83GHz and the ATI x1400. Anecdotal data suggests that the x1400 has heating issues vs. the other ATI chips from that series (the x1300 runs significantly cooler and is almost the same). Also some Thinkpad heat sinks are just seated poorly, there are links to guides to modifying them somewhere on Thinkwiki if you are so inclined.

Right now I'm in a 65F/18C room and $ sensors reads 44C. Here is a list of things I have done to lower heat with some success:

--replace heat sink (fan bearing failed), clean chips and new heat sink assembly properly and add new thermal compound (Arctic Silver)
--run thinkfan daemon with these thinkfan.conf settings:

(0,     0,      40)
(1,     33,     45)
(2,     35,     41)
(3,     37,     43)
(4,     41,     45)
(5,     44,     47)
(7,     46,     32767)

--EDIT: Add pcie_aspm=force i915.i915_enable_rc6=1 to kernel boot line in GRUB as ad hoc fix to kernel power regression issue: less power usage = less wattage = less heat, in theory
--Set AC and battery CPU to "balanced" in BIOS
--Run cpufreq daemon, load cpufreq_conservative module to lower CPU speeds when idle. Questionable how effective this is practically as far as power use
rc.conf:

MODULES=(acpi-cpufreq cpufreq_conservative)

/etc/conf.d/cpufreq:

governor="conservative"
min_freq="1.00GHz"
max_freq="1.83GHz"

Follow the wiki here to figure out what settings are valid, you probably have a different CPU

--Experiment with BIOS video settings--can't recall ATM but IIRC there is a line for video at boot that I found lowered temps a few degrees after changing it back and forth
--last but not least, use one of those external laptop fans that runs on AC power.

Last edited by nathan28 (2011-11-02 23:26:00)

Arch Linux

#1 2011-10-09 07:17:26

Unreasonably high temperatures

#2 2011-10-10 12:13:37

Re: Unreasonably high temperatures

#3 2011-10-11 15:17:27

Re: Unreasonably high temperatures

#4 2011-10-11 15:41:44

Re: Unreasonably high temperatures

#5 2011-10-11 20:44:50

Re: Unreasonably high temperatures

#6 2011-10-27 11:59:45

Re: Unreasonably high temperatures

#7 2011-10-27 13:31:08

Re: Unreasonably high temperatures

#8 2011-10-29 11:02:28

Re: Unreasonably high temperatures

#9 2011-11-01 15:50:06

Re: Unreasonably high temperatures

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