[lm-sensors] ASUS Sabertooth Z77 / nct6775.ko report

Guenter Roeck guenter.roeck at ericsson.com
Sun Jun 10 17:42:33 CEST 2012


On Sun, Jun 10, 2012 at 04:25:02AM -0400, Torbjörn Österdahl wrote:
> Sam 2012-06-09 klockan 23:30 -0700 skrev Guenter Roeck:
> > On Sat, Jun 09, 2012 at 02:35:18PM -0400, Torbjörn Österdahl wrote:
> > > I have got a Asus P8Z77-M PRO and have similar experiences.
> > > 
> > > - The standard lm-sensors package that comes with my distribution, (i:3.3.1/
> > > Ubuntu), does not include support for setting PWM fan speeds.
> > > - By downloading and compiling the nct6775 module from https://github.com/
> > > groeck/nct6775 these things work to statisfaction.
> > > - Temperatures as read from the chipset is low. Compared to temperatures
> > > measured by a thermometer in the case they are lower and does not go up as
> > > quickly when they system load increases. I.e. my idle system have a chipset
> > > temperature of 28 Degrees - they temperature in the case is meassured to 32.
> > > The loaded system reports a chipset temperature of 32 but the thermometer in
> > > the case reports 44!
> > > - Case temperature as read from the acpiz module are identical though.
> > 
> > I can't really comment on that. No idea how accurate the sensors are.
> > Some of the sensors (eg the CPU sensor if measured through PECI) are extremely
> > inaccurate at low temperatures.
> > 
> > > - hysteresis values, i.e. pwm3_auto_point1_temp_hyst, behave strange. It is
> > > depenant on the corresponding temp field and often takes negative values.
> > 
> > The hysteresis should show a constant difference to the matching temperature,
> > and is displayed as absolute temperature.
> > 
> > For example, assume pwm3_auto_point1_temp_hyst is set to 20000 and pwm3_auto_point1_temp
> > is set to 60000. If you change pwm3_auto_point1_temp to 30000, pwm3_auto_point1_temp_hyst
> > should change to -10000. Is that what you see ?
> 
> Yes. It reflects my observations. 
> 
> My expectation was that I should set the 'hysteresis' to determine how
> sensitive the circuit reacted to deviations from the target temperature.
> Now it appears that it does not matter if I set it or not, though. 
> 
That is pretty much what it should do. For example, if you set temp to 50000 and temp_hyst
to 45000, the respective pwm value should increase at 50 degrees C and decrease at 45 degrees C.
It will still react at those well defined temperatures, but the pwm value (and thus fan speed)
does not start to go up and down quickly if the temperature is around 50 degrees C.

If you think that does not work, please let me know. You'd have to observe the pwm value
around the switchover temperature for a while.

> > 
> > > - In Thermal Cruise mode it sometimes stops the fan completely which I consider
> > > unnecessary. I was not able to prevent this.
> > 
> > pwmX_stop_output is the lowest pwm value. It is only used if pwmX_stop_output_enable
> > is set, otherwise the output drops to 0. Can you try this ?
> 
> Yes. That works. Perfect. 
> 
Excellent.

> > Thanks,
> > Guenter
> 
> Another oddity is that sometimes(!?) I am not able to set values using
> sudo, i.e. 'sudo echo "1"
> > /sys/class/hwmon/hwmon2/device/pwm3_stop_output_enable'. It does not
> matter if I use 'sys/devices/platform' or '/sys/class/hwmon/hwmon2/' I
> often need to change to a root console first. Since I have not set any
> root password I am using 'sudo -i' which works nicely. 
> 
Should never work, really. As explained in the other e-mail, root permissions
don't extend to redirections.

Thanks,
Guenter




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