Which one says the right Temperature.

brot · Guru Joined: 06 Apr 2004 Posts: 322

Hi everyone. I recently bought a new fan for my opteron 170, and now i am really really confused.
Under load, i get the following Temperatures:

eccerr0r · Posted: Wed Jun 06, 2007 4:41 pm Post subject:

you may never know...

calibration, calculation, and measurement points all differ between each measurement system...

Only way to tell is to measure it with your own thermometer, which may or not be "accurate" due to proximity to where you really want to measure...
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Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

Jupiter1TX · Guru Joined: 24 Feb 2006 Posts: 546 Location: 3rd Rock

The easiest thing to do is compare lm_sensors reading with your MB reading.
Then modify the sensors.conf to correct for skew.

The most accurate way to check is to use a Temp Digital Infrared IR Non-Contact Thermometer.
http://www.directron.com/sensors.html

I am waiting on delivery of a DFI LANPARTY UT NF4 Ultra-D. Once i get it
installed i will give you an update on the adjustments i make in sensors.conf
so you can try.

With my current MB i have had to make a -5c adjustment in sensors.conf
Example:

eccerr0r · Posted: Wed Jun 06, 2007 5:13 pm Post subject:

keep in mind thermal sensors, specifically the thermistor, is nonlinear and a mere translation is inaccurate. Also a lot depends on how the circuitry is wired on the board - which may never be revealed to the public without reverse engineering.

Of the three systems in the OP, I'd throw out the lm_sensors reading since it's thermistor based, and I believe opterons have thermal diodes which tend to be more stable (not to mention ACPI is usually more accurate, but board-to-board and device-to-device variation can throw that off too).

On my p4, which does have a thermal diode, seems to match up more closely:

ACPI thermal_zone:
temperature: 43 C

lm_sensors:
temp2: +43.0 C (high = +65 C, hyst = +60 C) sensor = diode
_________________
Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

brot · Guru Joined: 06 Apr 2004 Posts: 322

Well, have been talking with my friend which was the previous owner of the board. He said that the sensor on the motherboard (in windows) was inaccurate, and i should look at the temps of the k8 sensor. the sensor on the motherboard just more or less guesses the temperature, because it has no direct contact to it.

Jupiter1TX · Guru Joined: 24 Feb 2006 Posts: 546 Location: 3rd Rock

You are correct eccerr0r. On the AMD just enable the K8temp module
to get the most accurate reading. MY K8temp reads 37c right now
and my CPU thermistor reads 42 with the 5c correction. So it actually
is reading 47. I guess i should have made a 10c correction to be more
accurate. +10c is common in my MB.

The K8temp reads the sensor in the CPU while the CPU thermistor is under the CPU
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