# CPU power Management



## Speedy (Jul 16, 2016)

Intel(R) Atom(TM) CPU D2500   @ 1.86GHz

```
dev.cpu.1.temperature: 55.0C
dev.cpu.0.temperature: 57.0C
```

This is the idle temperature. What can be done about lowering it? I think this CPU has some P-States?


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## tingo (Jul 16, 2016)

Why do you want to lower the *CPU* temperature when your machine is running?


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## Speedy (Jul 16, 2016)

tingo said:


> Why do you want to lower the *CPU* temperature when your machine is running?


Because I think it is too high for idling machine? Waste of power and unnecessary thermal stress.

Edit: You should not reply to a zero-reply thread if you have nothing to say.


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## tingo (Jul 16, 2016)

Why do you think that your Atom D2500 should have a lower idle temperature than 55 degrees Celsius? Do the Intel datasheets say that it should?


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## leebrown66 (Jul 16, 2016)

Maybe CPU scaling will be of interest?  There's a thread here, but be aware this talking about FreeBSD 7, so things may have changed.
BTW, that CPU maxes out at 100C (see here).


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## Remington (Jul 16, 2016)

Idle temperature is usually 43 for that processor.  Are you using cooling fan or is it in a cool room?

The processor is designed to work up to 100C so its within the operating spec.

You can run this test to push your cpu to full load and monitor the temperature.

`yes > /dev/null & yes > /dev/null

killall yes`

What does the readings say?


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## Murph (Jul 17, 2016)

Speedy said:


> Because I think it is too high for idling machine? Waste of power and unnecessary thermal stress.



The equilibrium temperature, on its own, when idle tells you nothing about power consumption.  If the system has reduced active cooling (i.e. fans, etc) to a minimum, there's quite possibly very little energy transfer occurring (i.e. power consumption).  As far as stress goes, continual thermal cycling between low and high temperature may well do far more long term damage than running at constant temperature in the middle of the manufacturer's specified safe operating temperature range.  Long term thermal cycling leads to long term physical damage, especially when there are multiple different materials with physical connections (and therefore a range of coefficients of thermal expansion producing physical stress and fatigue).  A good quality CPU should not be receiving any significant long term damage from running at a constant 55°C when it has a spec sheet maximum of 100°C.



Speedy said:


> Edit: You should not reply to a zero-reply thread if you have nothing to say.



tingo asked a perfectly reasonable, on-topic question.  I would have asked the very same question if I had looked at this thread prior to the other responses.  You gave very little information in your original post, so it is entirely normal and reasonable for people to ask about things which you omitted.


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## User23 (Jul 18, 2016)

It is old but still offers the right information: https://wiki.freebsd.org/TuningPowerConsumption

On FreeBSD 10.3

```
hint.p4tcc.0.disabled=1
hint.acpi_throttle.0.disabled=1
```
is disabled by default


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## kpa (Jul 19, 2016)

User23 said:


> It is old but still offers the right information: https://wiki.freebsd.org/TuningPowerConsumption
> 
> On FreeBSD 10.3
> 
> ...



On any CPU that supports EIST you should keep those disabled.


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## RedShift1 (Jul 23, 2016)

Those temperatures are nothing to worry about. It also depends on the cooling you have in your computer. If you want to make your CPU run cooler, disable any FAN thermal control in the BIOS or invest in better fans and heatsinks.


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## User23 (Jul 24, 2016)

RedShift1 said:


> Those temperatures are nothing to worry about. It also depends on the cooling you have in your computer. If you want to make your CPU run cooler, disable any FAN thermal control in the BIOS or invest in better fans and heatsinks.



Those 10W TDP CPUs are almost always passive cooled. Often the only fan in those systems is the PSU fan, if the system is not fanless with a external 12-16V DC PSU.


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