[lm-sensors] Coretemp misreading?

[Ed W]

Not that many folks dived in, but the conclusion to this was that 
swapping the L3426 processor with an X series fixed the mis-reading.  I 
presume therefore that this looks more like a kernel issue than an 
lm-sensors issue?  Who to file bug reports to about coretemp mis-reads?

Thanks

Ed W


On 26/10/2010 10:25, Ed W wrote:
> Hi, I have a pair of (identical) new supermicro machines and had some 
> significant issues getting accurate temps out of them.  Bios updates 
> (betas) have fixed most of them, but I'm finally stuck with the CPU 
> temps reading exceptionally high using the kernel coretemp module
>
> Board is the supermicro X8SIE-LN4F.  Processor is an intel L3426 (ie 
> the 45W part).
>
> Sensors 3.1.2 reads (loaded):
>
> coretemp-isa-0000
> Adapter: ISA adapter
> Core 0:      +81.0C  (high = +94.0C, crit = +100.0C)
>
> coretemp-isa-0001
> Adapter: ISA adapter
> Core 1:      +79.0C  (high = +94.0C, crit = +100.0C)
>
> coretemp-isa-0002
> Adapter: ISA adapter
> Core 2:      +81.0C  (high = +94.0C, crit = +100.0C)
>
> coretemp-isa-0003
> Adapter: ISA adapter
> Core 3:      +77.0C  (high = +94.0C, crit = +100.0C)
>
> Idle the temps are around 55-60C
>
> There is no bios CPU temp to compare against, all I get is a "Low" 
> reading normally, going up to a "Med" reading when the temps are as 
> above (there is also a "high", but unknown when that kicks in)
>
> Additionally there are some temps shown through the sensors module 
> (these were affected by the bios fixes)
>
> temp1:       +36.0C  (high = +60.0C, hyst = +55.0C)  sensor = thermistor
> temp2:       +78.5C  (high = +95.0C, hyst = +92.0C)  sensor = diode
> temp3:       +30.0C  (high = +80.0C, hyst = +75.0C)  sensor = thermistor
>
>
> The bottom one coincides with the bios "System Temp" and is believed 
> to be the thermistor at the back of the board.  Unknown what the other 
> two are.  The Temp2 tends to look a little like the average of the CPU 
> temps though?
>
>
> Basic sanity check though.  I take the lid off the machine and the 
> heatsink is completely cold at idle and slightly warm under load...  I 
> have reseated the heatsink on one of the machines as a sanity check, 
> no difference.  Both machines are reporting the same range of 
> temperatures under similar loads.  I checked temps using kernel 2.6.32 
> and 2.6.36 with similar results
>
> My best guess is that the CPU temp sensor is mis-reading.  However, is 
> this possible?  I understand the CPU temp is specified as an inversion 
> from the max value and hence in any case if the observed temp is wrong 
> then the point is still that my "margin" for safety is something like 
> the 94C - 81C = 13C from max temp?
>
> This machine needs to last long term, I'm currently a bit worried 
> about the reported temps - can anyone please shed some light on 
> whether this is just a bad reading and should be ignored?
>
> Thanks
>
> Ed W
>
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