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-   -   CPU temp? (http://www.linux-archive.org/debian-laptop/98947-cpu-temp.html)

"Dotan Cohen" 06-01-2008 06:41 AM

CPU temp?
 
What could explain the differences between these reported temperatures?

hardy2@hardy2-laptop:~$ acpi -V
Battery 1: charging, 22%, 02:26:55 until charged
Thermal 1: ok, 47.0 degrees C
AC Adapter 1: on-line
hardy2@hardy2-laptop:~$ sudo sensors
coretemp-isa-0000
Adapter: ISA adapter
Core 0: +43.0°C (crit = +100.0°C)

coretemp-isa-0001
Adapter: ISA adapter
Core 1: +45.0°C (crit = +100.0°C)

hardy2@hardy2-laptop:~$ cat /proc/acpi/thermal_zone/THM/temperature
temperature: 46 C
hardy2@hardy2-laptop:~$


Also, am I to believe that "crit = +100.0°C" means that the CPU can
get up to 100 degrees before damage? This is an Intel CoreDuo
processor, and my experience with Intels is that they break around 80
degrees. Though I've actually gotten an AMD well up over 100 degrees
by accident once, and it still runs fine, but I'm very suspicious that
an Intel would survive that.

Dotan Cohen

http://what-is-what.com
http://gibberish.co.il
א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-*-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

Robert Black 06-01-2008 02:24 PM

CPU temp?
 
Dotan Cohen wrote:

What could explain the differences between these reported temperatures?


Also, am I to believe that "crit = +100.0°C" means that the CPU can
get up to 100 degrees before damage? This is an Intel CoreDuo
processor, and my experience with Intels is that they break around 80
degrees. Though I've actually gotten an AMD well up over 100 degrees
by accident once, and it still runs fine, but I'm very suspicious that
an Intel would survive that.

Dotan Cohen



http://tinyurl.com/66d9hh
More than you want to know about your chip. Just have to find it.
Robert



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Paolo 06-01-2008 04:21 PM

CPU temp?
 
On Sun, Jun 01, 2008 at 09:41:35AM +0300, Dotan Cohen wrote:
> What could explain the differences between these reported temperatures?

> coretemp-isa-0000
...

2 degC betwwen cores doesn't sound too much, also considering param spread
etc. The ACPI value comes from other module - might be an average, and the
acpi module might use a different formula and/or different params (the
coretemp is likely more correct, being very hw-specific).

> Also, am I to believe that "crit = +100.0??C" means that the CPU can
> get up to 100 degrees before damage? This is an Intel CoreDuo

120+ degC actual silicon T isn't uncommon as max operating T. 100 degC
is likely a derating which allows for a reasonable margin before the
chip goes out of spec. Physical damage occurs at quite higher T.
Of course, don't expect much long-term reliabilty if you keep your chips
close to that limit for long time (or better, with high duty-ratio).

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paolo


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"Dotan Cohen" 06-01-2008 06:23 PM

CPU temp?
 
2008/6/1 Paolo <oopla@users.sf.net>:
> On Sun, Jun 01, 2008 at 09:41:35AM +0300, Dotan Cohen wrote:
>> What could explain the differences between these reported temperatures?
>
>> coretemp-isa-0000
> ...
>
> 2 degC betwwen cores doesn't sound too much, also considering param spread
> etc.

The 2 degree difference between core0 and core1 isn't what confused
me, rather, the different tempuratures reported by acpi, sensors, and
the /proc file.

> The ACPI value comes from other module - might be an average, and the
> acpi module might use a different formula and/or different params (the
> coretemp is likely more correct, being very hw-specific).

An average of what? According to sensors, the machine only has temp
sensors on the CPU dies, not on the hard drive or memory or whatever.
And the apci and /proc temps are not the average of the core temps.

>> Also, am I to believe that "crit = +100.0??C" means that the CPU can
>> get up to 100 degrees before damage? This is an Intel CoreDuo
>
> 120+ degC actual silicon T isn't uncommon as max operating T. 100 degC
> is likely a derating which allows for a reasonable margin before the
> chip goes out of spec.

Really? I've melted older (pentium 3,4) CPUs at around 80, probably
even less. I don't know how far the sensor on the P4 is from the die,
but it can't be _that_ far. AMD's I've seen get that hot and live
(well, once). I understand that they are made of the same materials in
similar processes, but the differences are probably akin to Huyndai
and BMW (same basic idea, huge quality difference).

> Physical damage occurs at quite higher T.
> Of course, don't expect much long-term reliabilty if you keep your chips
> close to that limit for long time (or better, with high duty-ratio).

I try not to :) I actually find that Arctic Silver can make a few
degree change in temp, even with a clean heatsink and a decent fan.

Dotan Cohen

http://what-is-what.com
http://gibberish.co.il
א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-*-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

Paolo 06-01-2008 07:14 PM

CPU temp?
 
On Sun, Jun 01, 2008 at 09:23:42PM +0300, Dotan Cohen wrote:
>
> An average of what? According to sensors, the machine only has temp

Tcore1+Tcore2/2 but ...

> sensors on the CPU dies, not on the hard drive or memory or whatever.
> And the apci and /proc temps are not the average of the core temps.

... see the point about different algo/params.
That's likely also different from lm-sensors, which knows of off-chip sensors
(beneath the CPU).

> Really? I've melted older (pentium 3,4) CPUs at around 80, probably
> even less. I don't know how far the sensor on the P4 is from the die,

silicon power devices can have Tlimit 175 degC, nanometer ICs are more
delicate of course, and each CPU family from each vendor comes with its own
in-spec and phy.damage T limits. Hopely the chip 'knows' its own limits,
and it shutdowns itself before melting. If its internal table says 100 degC,
well, that's likely so (though CPU vendor might keep the real value
undisclosed, for the usual reasons).
But if you're curious, check the very datasheet from the URL posted by others.

Yes, old CPU could melt rel. easily if allowd to, but not @T you mentioned,
you read the T from off-chip sensors, (to some extent close to case T),
which means likely the silicon itself was well above 100 degC, with hot spots
> 150 degC.
(Recent) CPUs check their T from on-chip sensor (basically, a diode), which
may be readable by some means (eg via MSR) by eg a program the same CPU is
running.
That's what the module coretemp does.

> but it can't be _that_ far. AMD's I've seen get that hot and live

afaikt, even old AMD's had on-chip arrangements for internal cut off
@T limit. I couldn't burn a K6 even leaving it without heatsink.
OTOH the electronics surrounding the CPU fail{s,ed} frequently, so there's
a lot of spare old CPU around ;).


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paolo


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