[mythtv-users] Slightly OT - Controlling the CPU fan

Mario Limonciello mario.mailing at gmail.com
Sun Aug 21 13:29:36 UTC 2005


Jim Reith wrote:

>> > Even though my Myth backend does not sit in the lounge, it does sit in
>> > the study and the fan noise is driving the family nuts to point they
>> > want the backend shutdown when they are in there.
>> >
>> > I have done heaps of searching around and can't seem to find any solid
>> > info but I would like to be able to throttle back the fan on the CPU
>> > when the backend is idling as it seems to most of the time.
>> >
>> > I have lm_sensors running and I know the speed of the fan, but I can't
>> > find any way to control it.  It is a Sempron 2400 sitting on a crappy
>> > generic mobo.  Also, I am sure I could afford to turn the fan down as
>> > the highest temperature the CPU has gotten to so far is 50 degree
>> > celcius (although it is winter-ish here in QLD, Australia atm).
>> >
>> > Anyways, does anyone have any suggestions other than sticking the box
>> > in the garage?
>>
>> You could buy a Zalman fan - they're very quiet. I have one and I've
>
>> been very pleased with it.
>
>
> Chances are the fan speed is controlled by the motherboard and the 
> only way you can really control it is by reducing the temp in the case.
>
> Since you said you were using lm_sensors I assume you've seen this page?
>
> http://knoppmythwiki.org/index.php?page=Power+Management
>
> I found that making my (3) disk drives sleep after being idle for 5 
> minutes dropped my case temperature 10 degrees
>
> mbmon -c 1 -t > starting_temp.log
>
>
> # more starting_temp.log
>
> Temp.= 55.0, 25.0, 44.0; Rot.= 4787,    0,    0
> Vcore = 1.65, 1.65; Volt. = 3.34, 4.92, 11.80, -10.74, -4.66
> Thu Aug 11 18:34:20 EDT 2005
>
>
> # more spundown_temp.log
>
> Temp.= 45.0, 25.0, 32.0; Rot.= 4591,    0,    0
> Vcore = 1.66, 1.65; Volt. = 3.34, 4.92, 11.80, -10.74, -4.63
> Fri Aug 12 05:43:42 EDT 2005
>
>
> <once the weather cooled off>
>
> root at mythtvbox:~# mbmon -c 1 -t
> Temp.= 43.0, 25.0, 32.0; Rot.= 4530,    0,    0
> Vcore = 1.65, 1.66; Volt. = 3.33, 4.92, 11.73, -10.74, -4.63
> Mon Aug 15 06:26:53 EDT 2005
> One of the other suggestions I've seen but not tried is to use 12v 
> fans but run them off the 5v supply so they spin slow and quiet. There 
> are also adapters so you can dial down the fan voltages with a little 
> pot. I agree that the Zalman fans are VERY quiet. I have one also. 
> I've also bought round IDE cables to help case airflow and it happens 
> that there are some on sale VERY cheap this week 
> http://store.yahoo.com/svcompucycle/clearance.html (at the bottom of 
> the page)
>
> One thing you want to make sure of is to not turn the fans down 
> manually and fry your CPU
>
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>
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>
If your fan is controlled by your motherboard, and temperature is what 
affects it - you can possibly set up some dynamic settings for cpu 
frequency.

My athlon64 supports an ondemand cpu governor.  I simply wrote a few 
rules for cpufreqd, and now my 3200+ will downclock to 1Ghz when there 
is no CPU usage.  When CPU usage goes up, so does CPU frequency, all the 
way up to what I think 2.2 ghz or so.

Luckily, my ASUS board supports slowing down the cpu fan when things 
cool down.  Call it crazy, but the CPU fan actually turns off when 
idling at 1ghz.  The loudest thing in the case ends up being my GPU fan, 
as I have a controller that turned down the speed on my PS fan, and i 
have a rheostat for the rest of the fans turned down to about 33 percent.


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