[lm-sensors] Interpreting lm-sensors's output
khali at linux-fr.org
Fri Mar 2 21:59:48 CET 2012
On Fri, 02 Mar 2012 15:27:57 -0500, Stefan Monnier wrote:
> >> OT1H the "high=70" and "crit=100" would seem to give me the answer, but
> >> OTOH I don't know whether I can trust them (actually, I hope some of
> >> the output is "wrong" since the sensor readings go up routinely to 80°
> >> during long compilations).
> > They are correct and you should trust them. If you reach 80°C then you
> > probably need better thermal dissipation or a different CPU / graphics
> > power management strategy.
> The thing that puzzles me is that this low-power mini-ITX board (fanless
> Brazos E350) is in a full-size ATX chassis (Antec Sonata) which
> previously held an high-power Athlon X2 board (first with the stock
> AMD heatsink+fan, and then later with a monster fanless heatsink), so
> I have a hard time understanding how this low-power board can heat up
> worse than the other one in the exact same context (same chassis,
> power-supply, devices, system fan spinning at the same speed, ...).
> The Athlon X2 barely reached 70°C in the hottest part of the summer,
> under full load.
Comparing a system with a CPU fan with one without doesn't necessarily
make a lot of sense. Sure, the chassis and system fan are the same, but
when you had a CPU fan it was the main factor for determining the CPU
temperature. Now the airflow in the chassis has become the main factor.
Also note that the values reported by k8temp / k10temp are essentially
relative values in pseudo-degrees C, so comparing them from one CPU
model to another is not meaningful either. What is meaningful is the
difference between the current temperature and the high (or critical)
limit. That is, the thermal margin.
If the CPU is really heating too much compared to what you would
expect, you should check that the heatsink is properly mounted with
thermal paste properly applied. If the CPU temperature is that high,
the heatsink should be very hot. If it's not then that would be the
problem. If it is, maybe you need a larger heatsink.
Also check that the air flow through the case is correct, i.e. enough
space on both sides of the fan to not block the air flow, and nothing
blocking the flow inside the chassis either. Placing the fan at the
right place is also important, if you have the choice. You wouldn't
notice these issues as long as the CPU itself had a fan, but not it
As a final note, your new processor package integrates a GPU. This
could also explain the greater temperatures you get, as modern GPUs run
fast and can heat a lot too. And the radeon driver not not excel on the
power management front, at least not with the default settings.
> > BTW, you may have other (unsupported) sensors on the board... Give a
> > try to http://dl.lm-sensors.org/lm-sensors/files/sensors-detect
> > and report the full output.
> OK, I finally added "acpi_enforce_resources=lax" and loaded the it87
Not necessarily a good idea in the long run, but I'll assume you know
what you're doing.
> module, which does give me a bit more data:
> Adapter: PCI adapter
> temp1: +51.6°C (high = +70.0°C)
> (crit = +100.0°C, hyst = +97.0°C)
> Adapter: PCI adapter
> temp1: +52.0°C
> Adapter: ISA adapter
> in0: +3.06 V (min = +1.46 V, max = +1.98 V) ALARM
> in1: +1.07 V (min = +0.00 V, max = +1.52 V)
> in2: +2.23 V (min = +0.00 V, max = +1.52 V) ALARM
> in3: +0.01 V (min = +0.00 V, max = +1.52 V)
> in4: +1.02 V (min = +1.09 V, max = +0.83 V) ALARM
> in5: +1.52 V (min = +1.31 V, max = +0.78 V) ALARM
> in6: +1.12 V (min = +1.69 V, max = +2.69 V) ALARM
> 3VSB: +3.26 V (min = +0.00 V, max = +3.05 V) ALARM
> Vbat: +3.24 V
> fan1: 0 RPM (min = 20 RPM) ALARM
> fan2: 0 RPM (min = 20 RPM) ALARM
> temp1: +30.0°C (low = +0.0°C, high = +127.0°C) sensor = thermal diode
> temp2: -128.0°C (low = +13.0°C, high = -18.0°C) sensor = disabled
> temp3: -128.0°C (low = -67.0°C, high = -3.0°C) sensor = disabled
> intrusion0: ALARM
> So I guess the it87 "temp1" is a "motherboard" sensor. This one always
> stays much lower than the other two sensors.
Yes, I would assume the same, although it's strange that it is a
thermal diode, usually a thermistor is used for motherboard
temperature. You should check what the BIOS has to say with regards to
temperatures. If the motherboard really runs at 30°C then it seems
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