# CPU heat, lmsensors

## drwook

Hi guys,

Ok so I've got a Phenom II 920 and an K10N78FullHD-hSLI motherboard - been going fine for a year or so.  But I had a (cheap, generic - yes, I know...) PSU blow on me.  No problem, replaced the PSU (nice modular 600W be quiet jobby, so not a cheapo one), checked the CPU and mobo looked alright, cleaned the cpu and h/s after checking for obvious damage and re-applied some MX-2 thermal compound.

Now - works fine, seems to idle along at maybe 40C when the wife's booted in to windows.  when I have it on with a real OS, it's fine except when I push it (i.e. leave it compiling) at which point I get a thermal shutdown and the BIOS claims the CPU temperature goes over 100C.

So couple of issues.  One I've tried to get lm_sensors working so I can keep an eye - this is the best output I get, which doesn't appear to tell me the CPU temperature.  I've built k10temp into the kernel...  but haven't really used lm_sensors before so maybe have missed something obvious I need to do?

```

~ # sensors

w83627ehf-isa-0290

Adapter: ISA adapter

Vcore:       +1.34 V  (min =  +0.00 V, max =  +1.74 V)   

in1:         +1.29 V  (min =  +1.94 V, max =  +1.24 V)   ALARM

AVCC:        +3.34 V  (min =  +2.98 V, max =  +3.63 V)   

VCC:         +3.34 V  (min =  +2.98 V, max =  +3.63 V)   

in4:         +1.70 V  (min =  +0.05 V, max =  +0.98 V)   ALARM

in5:         +1.69 V  (min =  +0.36 V, max =  +0.82 V)   ALARM

in6:         +1.86 V  (min =  +1.72 V, max =  +1.95 V)   

3VSB:        +3.34 V  (min =  +2.98 V, max =  +3.63 V)   

Vbat:        +3.12 V  (min =  +2.70 V, max =  +3.30 V)   

in9:         +1.58 V  (min =  +0.53 V, max =  +0.26 V)   ALARM

fan1:          0 RPM  (min =  753 RPM, div = 128)  ALARM

fan2:       3125 RPM  (min =  547 RPM, div = 16)

fan3:          0 RPM  (min = 3515 RPM, div = 128)  ALARM

fan5:          0 RPM  (min =  878 RPM, div = 128)  ALARM

temp1:       +32.0°C  (high = -23.0°C, hyst = -85.0°C)  ALARM  sensor = thermistor

temp2:       +61.5°C  (high = +80.0°C, hyst = +75.0°C)  sensor = thermistor

temp3:       +61.0°C  (high = +80.0°C, hyst = +75.0°C)  sensor = thermistor

cpu0_vid:   +0.375 V

```

so 1/ it'd be nice to actually get the CPU temp, and 2/ some of those readings (and thresholds - e.g. temp1) look alarming?  Any advice/comments?

Secondly - I know the h/s is a little dusty so need to remedy that, but surely that can't be the cause of this level of overheating, insulation by dust?  I've got some air duster on order as I've ran out...  Any other suggestions though?  I was considering re-doing the compound again in case I managed to screw that up but don't think it's that...

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## NeddySeagoon

drwook,

A few things.  Thermal compound is actually quite a good thermal insulator but its has much better thermal properties than air, which is what would otherwise be in the gap between the CPU and heatsink.  At best, you only get three points of contact.

You have probably used too much thermal compound, so the heat stays in the CPU or maybe the CPU fan is not working for some reason.

As a very long shot, it is possible for the CPU to be damaged when the PSU went pop in such a way as it still works but draws a lot of extra power.

You need to edit sensors.conf for your motherboard. One of

```
 temp1:       +32.0°C  (high = -23.0°C, hyst = -85.0°C)  ALARM  sensor = thermistor

temp2:       +61.5°C  (high = +80.0°C, hyst = +75.0°C)  sensor = thermistor

temp3:       +61.0°C  (high = +80.0°C, hyst = +75.0°C)  sensor = thermistor 
```

will be the temperature in the CPU socket, between the CPU and motherboard.

Another will be the temperature in what should be a cool place on the motherboard.

Notice the sensor = thermistor statements.  Sensors are of two types thermistors, in which the resistance of a part varies as a funtion of temperature, and diodes, where the forward bias voltage changes by -2mV/DegC.  You need to see what your motherboard uses where and edit sensors.config to suit.

I don't think any of those temps are from k10temp as I get 

```
$ sensors

atk0110-acpi-0

Adapter: ACPI interface

Vcore Voltage:       +1.06 V  (min =  +0.85 V, max =  +1.60 V)

 +3.3 Voltage:       +3.50 V  (min =  +2.97 V, max =  +3.63 V)

 +5 Voltage:         +5.08 V  (min =  +4.50 V, max =  +5.50 V)

 +12 Voltage:       +12.44 V  (min = +10.20 V, max = +13.80 V)

CPU FAN Speed:      1151 RPM  (min =  600 RPM)

CHASSIS FAN Speed:   388 RPM  (min =  600 RPM)

CHASSIS FAN 2 Speed: 220 RPM  (min =  600 RPM)

CPU Temperature:     +30.0 C  (high = +60.0 C, crit = +95.0 C)  

MB Temperature:      +41.0 C  (high = +45.0 C, crit = +75.0 C)  

k10temp-pci-00c3

Adapter: PCI adapter

temp1:       +17.5 C  (high = +70.0 C, crit = +70.0 C)  
```

Note that I have two sets of sensor outputs.

I've edited the names in sensors.conf.  It looks like I ave the CPU (socket) and MB temps swapped.

I don't believe +17.5 C from k10temp-pci-00c3 either.

----------

## dmpogo

 *NeddySeagoon wrote:*   

> 
> 
> k10temp-pci-00c3
> 
> Adapter: PCI adapter
> ...

 

Yep, having some experience with k8temp - it seems often give a biased reading, like you need to add +20

----------

## drwook

Thanks.  I don't think I've used too much thermal compound....  Keeping that one in reserve after having a good clean out of the heat sink - seems to be idling along at 36.5 if lm_sensors isn't lying, so I think it was just the dust insulating :-/  I recompiled xulrunner and firefox while watching and it peaked at 50 briefly, which I don't think is too bad.

That said I'm about to leave it compiling away kde 4.5.2 so that should prove it one way or the other.

----------

## NeddySeagoon

drwook,

Heh - I assumed you would clean the grot out of the heatsink in the course of applying new thermal paste.

That breaks rule 1. Never assume.

It sounds like you are on the right track.

----------

## Odysseus

 *NeddySeagoon wrote:*   

> drwook,
> 
> Heh - I assumed you would clean the grot out of the heatsink in the course of applying new thermal paste.
> 
> That breaks rule 1. Never assume.
> ...

 

Neddy, I was thinking the same thing. A good rule to follow, is any time your box needs to be opened for repair or upgrade, that is the time for PM (preventative maintenance). It only takes a couple of minutes to clean out the dust bunnies while the case is already open, but it may take hours to troubleshoot a mysterious problem that turns out to be heat related later.

Ciao

----------

## Herring42

I have had a number of failures of the power supply fan, one of which lead to the a transformer in the power supply getting so hot, it melted the solder holding it to the PCB, and it dropped out.

Amazingly, the rest of the PC was fine! I put a spare power supply in, and it lasted another year.

Moral of the story: Power supplies, even quite expensive ones, have cheap fans that are usually not monitored at all, and often fail.

----------

## Chiitoo

While probably not helpful in any way, I feel like posting my readings for a Phenom II X6 1090T.

```

k10temp-pci-00c3

Adapter: PCI adapter

temp1:       +35.6 C  (high = +70.0 C, crit = +67.0 C)  

it8720-isa-0228

Adapter: ISA adapter

in0:         +1.26 V  (min =  +0.00 V, max =  +4.08 V)   

in1:         +1.49 V  (min =  +0.00 V, max =  +4.08 V)   

in2:         +3.33 V  (min =  +0.00 V, max =  +4.08 V)   

in3:         +3.02 V  (min =  +0.00 V, max =  +4.08 V)   

in4:         +3.06 V  (min =  +0.00 V, max =  +4.08 V)   

in5:         +2.99 V  (min =  +0.00 V, max =  +4.08 V)   

in6:         +4.08 V  (min =  +0.00 V, max =  +4.08 V)   

in7:         +3.04 V  (min =  +0.00 V, max =  +4.08 V)   

Vbat:        +3.22 V

fan1:       2288 RPM  (min =   10 RPM)

fan2:          0 RPM  (min =    0 RPM)

fan3:       2027 RPM  (min =    0 RPM)

fan5:          0 RPM  (min =    0 RPM)

temp1:       +36.0 C  (low  = +127.0 C, high = +127.0 C)  sensor = thermistor

temp2:       +39.0 C  (low  = +127.0 C, high = +70.0 C)  sensor = thermal diode

temp3:       +47.0 C  (low  = +127.0 C, high = +127.0 C)  sensor = thermistor

cpu0_vid:   +0.413 V

```

I haven't really even started to get into the settings of the sensors yet, only scanned/tested/installed the modules/kernel drivers for them and got it running and this can be seen from the readings I guess...

The most peculiar thing to me is the absence of +12~ V as well as the cpu0_vid V...

All in all it seems messed up to me.

Been meaning to try another PSU altogether but... so lazy...

----------

## dmpogo

To get right voltages (especially +12V and +5V) you need correct recalculation formulas for your motherboard set up in /etc/sensors3.conf .  If the manufacturer was not forthcoming with it (and in my memory only Tyan used to provide lm_sensors   sensors.conf file) and nobody guessed/reversed engineered it,   you are out of luck.

----------

## Chiitoo

 *dmpogo wrote:*   

> To get right voltages (especially +12V and +5V) you need correct recalculation formulas for your motherboard set up in /etc/sensors3.conf .  If the manufacturer was not forthcoming with it (and in my memory only Tyan used to provide lm_sensors   sensors.conf file) and nobody guessed/reversed engineered it,   you are out of luck.

 

I more or less figured something like that might be in play but I'm not too confident with this PSU as it keeps making these "bzzzt" sounds in a random'ish fashion as well.  xD

----------

## NeddySeagoon

Chiitoo,

If your A/D converter runs off 5v, it will have a full scale reading of 5v. If its a 3.3v, its full scale reading will be 3.3v.

Any voltages outside the 0v to full scale have to be scaled into that range by external resistors.

The exact numbers reported by lm-sensors are not too important, its deviations from the normal you need to be concerned about.

Your PSU is fine, or your hard drives would not spin up.

Look in the config file to see if your motherboard is listed in comments.  Fixing the readings may be as easy as uncommenting some lines and commenting others.  I think you need to look in the it87 section.

----------

