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I have dual boot on my machine - Windows Vista and Fedora 12.

I have noticed that while I am on Vista, the fan runs only intermittently, but while I am on Fedora, it runs continuously. I have tried to tweak the power and CPU settings for Fedora, but did not get anywhere.

Should I be worried that the fan is running continuously? Or is it okay, the fan is just doing its job?

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Maybe your tasks taking more CPU hence the Fans running continuously. Run sensors and update the question with sensor report –  subanki Sep 13 '10 at 6:02
    
Have you tried setting another cpu governor and monitored the temperature under Linux? –  Bobby Sep 13 '10 at 7:52
    
@subanki: Okay, I will. Although the question I am asking here is whether there is a reason to worry if the fans run continuously. –  Lazer Sep 13 '10 at 7:58
    
@Lazer Well see the thing is the fan runs at a faster speed and maybe continuously when your CPU is heating up fast. So According to me its bad to get your cpu heated that much but one of friend has a similar problem and he is using his PC like that for near about 1 and half year. So maybe you also dont need to worry –  subanki Sep 13 '10 at 8:12
    
My wife's laptop is like that. Fan always runs like crazy and it pumps out all kinds of heat. Seems to be normal for it (Toshiba). OTOH, mine only runs about half the time (Thinkpad). –  Brian Knoblauch Sep 13 '10 at 19:53

4 Answers 4

up vote 2 down vote accepted

The answer is maybe.

Fans are expendable components and whey will fail over time. The only question is when.

I'll just quote Wikipeida here

Sleeve bearing fans use two surfaces lubricated with oil or grease as a friction contact. Sleeve bearings are less durable as the contact surfaces can become rough and/or the lubricant dry up, eventually leading to failure. Sleeve bearings may be more likely to fail at higher temperatures, and may perform poorly when mounted in any orientation other than vertical. The lifespan of a sleeve bearing fan may be around 40,000 hours at 50 °C. Fans that use sleeve bearings are generally cheaper than fans that use ball bearings, and are quieter at lower speeds early in their life, but can grow considerably noisier as they age.

Rifle bearing fans are similar to sleeve bearing, but are quieter and have almost as much lifespan as ball bearings. The bearing has a spiral groove in it that pumps fluid from a reservoir. This allows them to be safely mounted horizontally (unlike sleeve bearings), since the fluid being pumped lubricates the top of the shaft.[4] The pumping also ensures sufficient lubricant on the shaft, reducing noise, and increasing lifespan.

Ball bearing fans use ball bearings. Though generally more expensive, ball bearing fans do not suffer the same orientation limitations as sleeve bearing fans, are more durable especially at higher temperatures, and quieter than sleeve bearing fans at higher rotation speeds. The lifespan of a ball bearing fan may be around 63,000 hours at 50 °C.

Fluid bearing fans have the advantages of near-silent operation and high life expectancy (comparable to ball bearing fans). However, these fans tend to be the most expensive. The enter bearing fan is a variation of the fluid bearing fan, developed by Everflow.

Magnetic bearing or maglev fans, in which the fan is repelled from the bearing by magnetism.

So having fan on all the time will decrease its lifetime. How big impact there will be on fan's lifetime depends on conditions in which it operates. Fans usually die because dust gets into their bearings and damages them. After that fan will slow down and start emitting grinding noises. This will reduce airflow causing even more dust to accumulate and increase of the temperature. As temperature increases, dust will start to bake. At one point it will into into black solid substance and grinding noise will become even louder and fan speed will decrease even more causing temperature to increase. Sometime after this step, serious overheating problems will appear and computer will start to shutdown. At one point fan will fail and will have to be replaced.

If the fan and heatsinks are regularly cleaned, the impact from dust will be much smaller and fan will have longer lifetime.

So in the end if you can regularly clean the fan, then in my opinion there is no great cause of concern. If you can't regularly clean the fan, then having it running continuously will decrease its lifetime. Unfortunately, I'm unable to estimate by how much will the lifetime be decreased, so I don't know if it will make an impact on the lifetime of the whole computer.

Also keep in mind that laptop fans are usually more expensive than standard desktop fans.

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There's a flaw in your analysis: barring poorly-supported hardware, the choice is between running the fans at reduced speed all the time and running the fans at full speed some of the time. I, for one, have no idea which one is worse in typical conditions. –  Gilles Sep 13 '10 at 19:39
    
@Gilles No, that is not the choice. I see no way to conclude that fan behave in the way you describe. Why would heat dissipation system wait for amount of accumulated heat to reach the point where the fan needs to run at high speed? Next: On laptops usually in BIOS there is a list of temperatures and fan speeds. Once the temperature passes a certain threshold fan speed will change accordingly. In my answer I focused on answering the question itself and not speculating on the causes of increased fan speed (because everyone else did that). –  AndrejaKo Sep 13 '10 at 21:04
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@Gilles If I had to speculate, I'd say the reason for continuous running is that cpufreq is either not installed correctly or set to have CPU on full power all the time and that is the reason why fan does not cease operation at certain intervals. Also, it is extremely unsafe to actually let operating system itself regulate fan speeds directly, so operating systems by themselves often do not attempt to directly control fan speed. –  AndrejaKo Sep 13 '10 at 21:09
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Laptops on which fan control depends on the OS (if only because an OS driver provides an ACPI table in the form of a binary blob — at least the “list of temperatures and fan speeds”, if not the code that used it, may come from the OS) definitely exist. I don't know whether the proportion of such machines is more like 10% or 90%. I agree that it's unsafe, but it's become common on consumer hardware since the late 1990s or so. I agree with your speculation on cpufreq. –  Gilles Sep 13 '10 at 22:47
    
@Gilles The information you provided is to me very disturbing. –  AndrejaKo Sep 14 '10 at 11:48

Having the fan run continuously is not a cause for concern for anything other than your ears (and those of the people near you).

That said, it's usually a sign of poorly supported ACPI. Your distribution is likely to have a safe default setup where the fan runs all the time, because not having the fan run when it's needed could cause the machine to overheat and crash or worse.

There are a few things you can try to either make your computer heat less or make your fan run less. In particular, check that you've installed all laptop support packages and that you have CPU speed throttling enabled (I don't know how this is done on Fedora).

If the easy route leads nowhere, your best bet to get the fan to run only when needed is to look for information for running your exact laptop model under Linux. Sometimes the information is some arcane hardware-specific setting (e.g. load a binary blob). Once you find information about your particular hardware, adapting it to your distribution tends to be the easy part.

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I am not sure if it will work but its worth a try , Go here and do the script

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Although this is obvious and not OS related as your question seems to relate to.

Most laptops never get cleaned and if it is clogged with dust it may contribute to this. A Toshiba I had ran the fan always and after cleaning, only rarely.

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