# Core 2 Duo and core temperature? [SOLVED]

## Paapaa

What do I need to do in order to read the core temperature of my Intel Core 2 Duo (C2D - just for searches) CPU? Is lm_sensors able to read straight from core? I only need the temperature, I don't need GUIs or anything like that.

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## Paapaa

Found something. I need to enable SENSORS_CORETEMP from kernel. Can I read the temperature directly from somewhere or do I have to use lm_sensors?

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## platojones

This may not be the answer to your question, but I think most motherboards have a sensor chipset which reads the temperature registers on the cpu.  lm_sensors provides the driver interface for that motherboard sensor chipset.  I suspect you can probably directly read the cpu temperature registers, but I would have no idea how to do it or why that would be necessary, since the mb sensor chipset provides the same information.  The intel website would probably have some more information on the subject though.

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## paulbiz

Yeah, compile the kernel modules and also emerge sys-apps/lm_sensors. I'm using lm_sensors with these modules active:

```
MODULE_0=abituguru3

MODULE_1=coretemp
```

In my case the Abit motherboard sensors only shows a single "CPU" temperature. The "coretemp" sensor will read the cores individually.

Here's my "sensors" output using this config:

```
abituguru3-isa-00e0

Adapter: ISA adapter

CPU Core:               +1.35 V  (min  +0.00 V, max  +1.65 V)

DDR2:                   +2.10 V  (min  +1.70 V, max  +2.50 V)

DDR2 VTT:               +1.05 V  (min  +0.85 V, max  +1.25 V)

CPU VTT:                +2.40 V  (min  +1.90 V, max  +2.90 V)

NB 1.2V :               +1.47 V  (min  +1.15 V, max  +1.75 V)

SB 1.5V:                +1.60 V  (min  +1.25 V, max  +1.85 V)

HyperTransport:         +1.28 V  (min  +1.00 V, max  +1.50 V)

ATX +12V (24-Pin):     +12.42 V  (min  +9.60 V, max +14.40 V)

ATX +12V (4-pin):      +12.54 V  (min  +9.60 V, max +14.40 V)

ATX +5V:                +5.04 V  (min  +3.99 V, max  +6.00 V)

ATX +3.3V:              +3.38 V  (min  +2.64 V, max  +3.94 V)

ATX 5VSB:               +5.19 V  (min  +3.99 V, max  +6.00 V)

CPU:                      +23°C  (high =   +75°C, crit =   +85°C)

System :                  +29°C  (high =   +55°C, crit =   +65°C)

PWM Phase1:               +51°C  (high =  +125°C, crit =  +135°C)

PWM Phase2:               +51°C  (high =  +125°C, crit =  +135°C)

PWM Phase3:               +50°C  (high =  +125°C, crit =  +135°C)

PWM Phase4:               +48°C  (high =  +125°C, crit =  +135°C)

PWM Phase5:               +47°C  (high =  +125°C, crit =  +135°C)

CPU FAN:               2820 RPM  (min  300 RPM)

SYS FAN:               1500 RPM  (min  300 RPM)

AUX1 FAN:              1500 RPM  (min  300 RPM)

AUX2 FAN:                 0 RPM  (min  300 RPM)

AUX3 FAN:                 0 RPM  (min  300 RPM)

coretemp-isa-0000

Adapter: ISA adapter

Core 0:      +24°C  (high =   +85°C)

coretemp-isa-0001

Adapter: ISA adapter

Core 1:      +24°C  (high =   +85°C)
```

Also should add that the lm_sensors auto-detect didn't work for me. It detected a lot of wrong sensor chipsets, and did not detect the one I actually have. I just manually set it in the config (as shown above) and it is good now. :)

Hope that helps!

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## Paapaa

Thanks, but I figured out that lm_sensors is NOT needed at all. As expected.

linux/Documentation/coretemp revealed that the core temperature can be read directly from /sys filesystem - I found it at /sys/devices/platform/coretemp.N/temp1.input where N is the core index (0, 1, 2 etc.). So all that is needed is the kernel module. That's it.

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## paulbiz

Great info, I'll attempt to add it to my brain  :Smile:  Thanks.

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## platojones

Yes thanks for replying with that information.  Since I've been using lm_sensors so long, I never bothered to look for anything else.  I had actually built the coretemp module, but never loaded it before.  I did notice this in my dmesg though after playing with it:

```

coretemp coretemp.0: Using undocumented features, absolute temperature might be wrong!

coretemp coretemp.1: Using undocumented features, absolute temperature might be wrong!

```

Good to know it's available though.

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## Paapaa

Yeah, coretemp gives million times more accurate temperature readings than external MB sensors which try to guessimate the actual temperature. You should definitely use internal sensor if it is available.

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## dpetka2001

could someone tell me where i can find the option to build this in the kernel?? i am not able to locate it...

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## Paapaa

 *dpetka2001 wrote:*   

> could someone tell me where i can find the option to build this in the kernel?? i am not able to locate it...

 

There is a useful search function in kernel setup. Just type "/coretemp" without the quotes. It'll show you the actual location of the option I mentioned above.

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## dpetka2001

ok the following is under hardware monitoring hardware monitoring and also what search for coretemp shows me coretemp...i don't see such an option however...should i also activate something else in the kernel? thanks in advance...

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## Paapaa

See this line when looking at SENSORS_CORETEMP help page:

"Depends on: HWMON && X86 && EXPERIMENTAL"

You must have them all enabled. Most likely you are missing the EXPERIMENTAL. You can search it again with /experimental and enable it. That should allow you to see the SENSOR_CORETEMP option.

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## dpetka2001

yes that did the trick...thanks for your help...

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