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Possible Duplicate:
CPU usage at 100% for several hours
Is it ok to have 100% CPU usage constantly

I wonder which case is more harmful: high percentage of usage (>90%) vs high temperature (> 70 or 80 celcius degree), both for several hours?

I only know high temperature is bad, but I am not sure about high percentage of CPU usage.

If one can choose between "higher usage and lower temperature" vs "lower usage and higher temperature", by for example scaling CPU frequency and using command cpulimit in Ubuntu, what is the recommendation for choice?

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Tim
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3 Answers3

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If one can choose between "higher usage and lower temperature" vs "lower usage and higher temperature", by for example scaling CPU frequency and using command cpulimit in Ubuntu, what is the recommendation for choice?

You can't. Higher usage means higher temperature. Lower usage means lower temperature.

  • Underclocking your CPU frequency with cpufreq will only affect the percentage of CPU usage without lowering the temperature.

    The percentage is an absolutely meaningless value. With the exact same workload, your percentage might go up or down when under- or overclocking your CPU. But it's still the same workload, so any potential harm (and I'm not sure there is any) caused by usage will be exactly the same.

  • Likewise, cpulimit limits the CPU usage, thus keeping percentage and temperature low.

I only know high temperature is bad, but I am not sure about high percentage of CPU usage.

How hot is bad depends on each individual CPU. Your specific CPU will automatically shut down at 105ºC to prevent damage (source).

Nevertheless, 80ºC is a little hot. Even at 100% load, you should be able to stay below that temperature with appropriate cooling.

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Dennis
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High percentage of CPU usage should not be harmful, since CPUs does not have any moving parts, that degrade after some amount of usage.

Theoretically it could, but I've yet to see a failed CPU because of high usage. (You can even safely use them 24/7/365.)

Heat is another problem which will reduce CPU life. (Another one is overclocking.) It correlates with usage and the more heat is produced, the shorter the lifetime.

But again, appropriate cooling that keeps temperatures in the „middle region” of the specification range will enable continuous usage.

In my opinion it boils down to this: if you can keep the temperature low, the percentage of the usage does not matter.

lgarzo
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If we look at this question from an abstract point of view, then strickly speaking high temperature is more harmful, because CPUs do have temperature limits, but they don't have utilization limits. As far as the manufacturer is concerned they are made to be used 100% 24h/day. There is no spec specifying how long they will last at continuous 100% usage, but there is a max temperature spec.

Note: It's not really possible to answer this question properly if you don't specify values for "high load" and "high temperature", so I have to keep the answer in the abstract realm.

devius
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