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Old 05-31-2007, 10:56 PM   #1
Registered: Oct 2004
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LM-Sensors Confusion

I have a Gigabyte 945GZ mainboard, whose sensors are detected as "it8718-isa-0290" by sensors-detect. I've looked through the /etc/sensors.conf file, and have seen references to it87-*, it8716*, etc., but none that are specific to my it8718. The sensors.conf file is very confusing looking to me, and I am hoping someone can give me some clarification on how to proceed.

Currently, my sensors output looks like:
root [/etc] $ sensors
Adapter: ISA adapter
in0:       +1.20 V  (min =  +0.00 V, max =  +4.08 V)   
in1:       +1.82 V  (min =  +0.00 V, max =  +4.08 V)   
in2:       +3.58 V  (min =  +0.00 V, max =  +4.08 V)   
in3:       +4.08 V  (min =  +0.00 V, max =  +4.08 V)   ALARM
in4:       +3.18 V  (min =  +0.00 V, max =  +4.08 V)   
in5:       +0.03 V  (min =  +0.00 V, max =  +4.08 V)   
in6:       +1.28 V  (min =  +0.00 V, max =  +4.08 V)   
in7:       +4.08 V  (min =  +0.00 V, max =  +4.08 V)   ALARM
in8:       +4.08 V
fan1:     1844 RPM  (min =   10 RPM)                   
fan2:        0 RPM  (min =    0 RPM)                   
fan3:        0 RPM  (min =    0 RPM)                   
temp1:       -54C  (low  =  +127C, high =  +127C)   sensor = thermistor   
temp2:        -2C  (low  =  +127C, high =  +127C)   sensor = thermistor   
temp3:       +23C  (low  =  +127C, high =  +127C)   sensor = diode   
vid:      +1.088 V
You can see how the temps are obviously way off. I don't know which sensor is which, etc. The BIOS shows my CPU temp at 35C.

Help will be appreciated.
Old 06-01-2007, 10:30 AM   #2
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The IT8718 is a Super I/O chip manufactured by ITE. A Super I/O chip controls all sorts of I/O from floppy drives to joysticks to keyboards to fans. Some of the I/O are dedicated (e.g., the fans) some are general purpose I/O (firmware configured by the mobo designer), and some are both. The product line began with IT8702 -> IT8705 -> IT8712 -> IT8716 -> IT8718. They are all pin compatible, that is an IT8718 can be used in place of an IT8702. However, some functions of the IT8718 would not be usable in older equipment designed to use the IT8702.

Unfortunately you can't use a generic configuration, you have to know how the Gigabyte engineers designed the circuitry external to the it8718 for your sepcific motherboard. For example, the allowable input voltage range to the it8718 is 0V - 4.096V. Hence, to monitor anything outside this range, you need to use a voltage divider. But, what did the Gigabyte designers choose to correlate 4.096V with for each voltage? Does the 12V rail provide a 4.096V input to the it8718 at 12V or 15V or 13V or ... you get the picture?

You also don't know which inputs are being used. I suspect not all of them are being used; even if an input is unused, it will report a value. I can guess by looking at them, but it's still just a guess.

I would agree that, unless you have frozen parts on the motherboard, your temperatures are wrong. Once again, you don't know wht type of sensor the Gigabyte engineers used. Is it a thermistor, a diode, or a diode connected transistor?

lm_sensors is neat but it's not really capable of providing true monitoring. The safe-maximum curves for silicon devices like microprocessors are not simply straight lines. It doesn't appear to me that lm_sensors is able to define rules any more complex than straight-line linear. It also doesn't provide enough parameters to understand what is really going on. Take anything lm_sensors tells you with a grain of salt.

You would probably be reasonably safe using the configuration for a similar motherboard using the it87-* or it8716, but maybe not. The best thing to do is send Gigabyte's technical support an e-mail and ask. That's what I did and they told me what I needed to know. Of course, I sent it from work with my work signature attached (which includes the lines Digital Systems, Design Assurance Engineer - Reliability & Safety) so that may have helped.
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Old 06-08-2007, 07:49 PM   #3
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I'm trying to read up on temperatures because I am giving my computer a quiet makeover. I've got lmsensors and x-sensors .46 going. I just tried sensors and got this:

kevin@kevin-desktop:~$ sensors
Adapter: ISA adapter
CPU core: +3.10 V (min = +3.10 V, max = +2.33 V) ALARM
+2.5V: +3.10 V (min = +2.37 V, max = +2.62 V) ALARM
I/O: +3.23 V (min = +3.13 V, max = +3.47 V)
+5V: +3.25 V (min = +4.51 V, max = +5.50 V) ALARM
+12V: +7.87 V (min = +10.81 V, max = +13.20 V) ALARM
CPU Fan: 4560 RPM (min = 0 RPM, div = 4)
P/S Fan: 1461 RPM (min = 0 RPM, div = 4)
SYS Temp: +43.0C (high = +45C, hyst = +40C)
CPU Temp: +23.9C (high = +60C, hyst = +55C)
SBr Temp: +26.3C (high = +65C, hyst = +60C)

I've got 4 alarm! Is that bad? What does that mean? Did I hook my Power Supply up wrong? and while I'm at it, What is SBr? What is hyst? Tell me more about those temperatures, how high can I let SYS get, since it is close. Why are the other two so low?
Old 04-10-2008, 01:56 PM   #4
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Thumbs up weibullguy's the man

weibullguy, you clearly know what you're talking about. I also have the IT87xx chip on my P35-DS3L and i was getting a wide range of reported temps from various programs. I eventually decided to use Gigabyte's own Windows monitoring/overclocking program, EasyTune5Pro, and you've made me at peace with trusting the motherboard's temp report above any other programs.. Had no idea there was so much more calculation involved in reporting PC temperatures.
Old 04-10-2008, 02:38 PM   #5
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If you go through the complete readme on LM_senors you will see that you can put pretty much whatever equation you want to for any sensors. It takes a little time and effort to "dial it in" but once you do it is done (for that particular motherboard model. You can usually find a good start on your Lmsensors by searching on the .conf and your motherboard.

The best way to check any of these monitors out is to check them against what the BIOS monitors are saying(PITA). The guys who setup the bios no exactly how stuff was arranged on the motherboard.



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