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cogent
n00b
Joined: 10 May 2005
Posts: 66
Location: New Jersey, USA
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 Posted: Mon Jun 05, 2006 3:41 am Post subject: whacky CPU readings with lm_sensors and it87 |
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Recently I decided to set up lm_sensors. After everything was set up I noticed that the CPU temp was jumping around crazily.
The temperature jumps from 1C to 36C and so on... I think I got a -9C at some point.
My hardware is an elitegroup (ecs) nforce3 motherboard. The i2c modules I have loaded are:
i2c_isa
i2c_nforce2
it87
I did RTFM the sensors.conf but that didn't work. I tried changing around the sensor type but that didn't do anything, the M/B Temp is reported correctly so I think the sensor type is correct.
Would I have to figure out some formula for this to work properly? |
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NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 55196
Location: 56N 3W
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| Posted: Mon Jun 05, 2006 11:17 am Post subject: |
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cogent,
The it87 is a general purpose sensor chip. Different motherboard suppliers use it in different ways.
If an indicated output is wrong and extreme (one of my temps is always 127C) or varies wildly over short spaces of time, the input is probably not used on your board.
When a reading is stable but plain wrong, you may well need to fiddle with the equations.
Look for inputs being swapped about too. Like the +5v being indicated as -12 ...
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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widan
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Joined: 07 Jun 2005
Posts: 1512
Location: Paris, France
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| Posted: Mon Jun 05, 2006 3:20 pm Post subject: Re: whacky CPU readings with lm_sensors and it87 |
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| cogent wrote: | Recently I decided to set up lm_sensors. After everything was set up I noticed that the CPU temp was jumping around crazily.
The temperature jumps from 1C to 36C and so on... I think I got a -9C at some point. |
Maybe this channel is not connected at all (and the CPU temp is on another channel), or the sensor is a diode and not a thermistor (diodes are non-linear and need a look-up table, that's why the values may look weird).
| cogent wrote: | | I tried changing around the sensor type but that didn't do anything |
Did you run "sensors -s" after changing the sensor type ? It's not just a computation, it's something that must be sent to the sensor chip. If you did not run it, then try the "diode" setting again with it.
| cogent wrote: | | the M/B Temp is reported correctly so I think the sensor type is correct. |
That means nothing. Motherboard temperature is almost always a thermistor, but CPU can use either a thermistor (usually under the socket) or a diode (either internal to the CPU or external). |
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cogent
n00b
Joined: 10 May 2005
Posts: 66
Location: New Jersey, USA
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| Posted: Mon Jun 05, 2006 3:46 pm Post subject: |
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Yes I did do "sensors -s". But the diode sensor's values have a bigger range of jumps and are mostly negative, therefore I was discouraged by that.
If there is one, would I find the table of lookup values by finding the chip number then looking for it on google? |
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mbar
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Joined: 19 Jan 2005
Posts: 1991
Location: Poland
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cogent
n00b
Joined: 10 May 2005
Posts: 66
Location: New Jersey, USA
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| Posted: Mon Jun 05, 2006 11:28 pm Post subject: |
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Thank you. Now I know at least not to bother with lm_sensors for CPU temp.
Lesson learned: Don't buy cheap motherboards. |
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mbar
Veteran
Joined: 19 Jan 2005
Posts: 1991
Location: Poland
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| Posted: Tue Jun 06, 2006 7:46 am Post subject: |
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| Just "emerge acpi" and you can check CPU temperature with "acpi -V" |
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cogent
n00b
Joined: 10 May 2005
Posts: 66
Location: New Jersey, USA
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| Posted: Tue Jun 06, 2006 9:29 pm Post subject: |
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Thanks!
acpi -t | sed -e s/"Thermal 1: ok, "// -e s/".0 degrees C"// gives me exactly what I need.
Now I wonder, does superkaramba like text? |
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