[lm-sensors] IT8728 shows wrong CPU temperature

[Tomas Johansson]

Because, these are idle values:

BIOS:
SYS 34 C
CPU 32 C

lm-sensors:
temp1:        +34.0 C  (low  = +127.0 C, high = +127.0 C)  sensor = thermistor
temp2:        +31.0 C  (low  = +127.0 C, high = +127.0 C)  sensor = thermistor
temp3:        +25.0 C  (low  = +127.0 C, high = +127.0 C)  sensor = thermistor


And when i for example compile firefox temp3 will rise to around 45-50 C, while temp2 stays at 31 C.




> Date: Fri, 23 Mar 2012 01:14:56 -0700
> From: guenter.roeck at ericsson.com
> To: tomasx at hotmail.com
> CC: lm-sensors at lm-sensors.org
> Subject: Re: [lm-sensors] IT8728 shows wrong CPU temperature
> 
> On Fri, Mar 23, 2012 at 04:00:35AM -0400, Tomas Johansson wrote:
> > Hi!
> > 
> > I have a Gigabyte GA-P67A-UD5-B3 with a IT8728F, yesterday i upgraded to Linux
> > 3.3 and tested the new IT87 module.
> > As i will show below it shows wrong CPU temperature.
> > 
> > First:
> > 
> > temp1 shows system or motherboard if you want.
> > temp2 shows ?, probably unused
> > temp3 shows CPU but is 7-8 degrees wrong compared to BIOS (I know that temp3 is
> > CPU because it is the only temp value that differ under load)
> > 
> > 
> > BIOS at this moment in time showed:
> > SYS 34 C
> > CPU 32 C
> > 
> > 
> > coretemp-isa-0000
> > Adapter: ISA adapter
> > Physical id 0:  +36.0 C  (high = +80.0 C, crit = +98.0 C)
> > Core 0:         +36.0 C  (high = +80.0 C, crit = +98.0 C)
> > Core 1:         +35.0 C  (high = +80.0 C, crit = +98.0 C)
> > Core 2:         +33.0 C  (high = +80.0 C, crit = +98.0 C)
> > Core 3:         +35.0 C  (high = +80.0 C, crit = +98.0 C)
> > 
> > it8728-isa-0290
> > Adapter: ISA adapter
> > in0:          +1.08 V  (min =  +0.00 V, max =  +3.06 V)
> > in1:          +2.03 V  (min =  +0.00 V, max =  +3.06 V)
> > in2:          +2.96 V  (min =  +0.00 V, max =  +3.06 V)
> > in3:          +2.93 V  (min =  +0.00 V, max =  +3.06 V)
> > in4:          +0.24 V  (min =  +0.00 V, max =  +0.84 V)
> > in5:          +1.20 V  (min =  +0.00 V, max =  +3.06 V)
> > in6:          +1.55 V  (min =  +0.00 V, max =  +3.06 V)
> > 3VSB:         +3.38 V  (min =  +0.00 V, max =  +6.12 V)
> > Vbat:         +3.26 V  
> > fan1:        1056 RPM  (min =    0 RPM)
> > fan2:           0 RPM  (min =    0 RPM)
> > fan3:           0 RPM  (min =    0 RPM)
> > fan4:           0 RPM  (min =    0 RPM)
> > fan5:        1374 RPM  (min =    0 RPM)
> > temp1:        +34.0 C  (low  = +127.0 C, high = +127.0 C)  sensor = thermistor
> > temp2:        +31.0 C  (low  = +127.0 C, high = +127.0 C)  sensor = thermistor
> > temp3:        +25.0 C  (low  = +127.0 C, high = +127.0 C)  sensor = thermistor
> > intrusion0:  ALARM
> > 
> > 
> > 
> > Conclusion:
> > 
> > fan1, shows correct value.
> > fan5, shows correct value.
> > temp1 (system), shows correct value.
> > temp3 (CPU), shows wrong value, in this case 25 C instead of 32 C.
> > 
> I am a bit lost here. Why do you assume that temp2 (which would show roughly
> the correct temperature) is unused, and that temp3 is the CPU temperature ?
> Why not temp2=CPU and temp3=??? 
> 
> What happens if you run something challenging on the system ?
> 
> Guenter
 		 	   		  
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