[lm-sensors] Not detecting all fan RPMs

Guenter Roeck guenter.roeck at ericsson.com
Mon Mar 26 22:14:16 CEST 2012


On Mon, 2012-03-26 at 15:20 -0400, Glenn Hollowell wrote:
> Hey all-
> 
> I have an ASRock 880G Extreme motherboard running openSuse linux 12.1. I
> have been having difficulty seeing all of my chassis and power fan rpms
> using SENSORS. I have just upgraded to v3.3.2 with no luck.
> 
> The mother board has (5) fan plugins. Three of these are for chassis
> fans, and the other two are labelled "CPU fan" and "PWR fan". The CPU
> fan and one of the chassis fan (#1) mobo plugins are 4-prong, the others
> are 3-prong plugs. The pigtails from the 2 chassis fans are 3-prong, as
> is the power supply plugin. The CPU fan pigtail is a 4-prong.
> 
> Currently, I've got chassis fans plugged into CHA_FAN1 and CHA_FAN2, and
> I've got the power supply fan plugged into PWR_FAN1. The CPU fan is
> plugged into CPU_FAN1. There is an additional CHA_FAN3 plug on the
> motherboard.
> 
> In bios I get the following readings,
> 
> CPU fan 1 = 3750
> Chasis fan 1 = 1268 
> Chasis fan 2 = 1278 
> Chasis fan 3 = NA
> Power fan 1 = 878 
> 
> All of the above seem reasonable and fine.
> 
> Below is the output from SENSORS,
> users at dothom-user1:~> sensors
> nouveau-pci-0400
> Adapter: PCI adapter
> temp1:        +56.0°C  (high = +100.0°C, crit = +120.0°C)
> k10temp-pci-00c3
> Adapter: PCI adapter
> temp1:         +0.0°C  (high = +70.0°C)
> nct6775-isa-0290
> Adapter: ISA adapter
> Vcore:        +1.21 V  (min =  +0.00 V, max =  +1.74 V)
> in1:          +1.86 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
> AVCC:         +3.28 V  (min =  +2.98 V, max =  +3.63 V)
> +3.3V:        +3.28 V  (min =  +2.98 V, max =  +3.63 V)
> in4:          +0.14 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
> in5:          +1.68 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
> in6:          +0.14 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
> 3VSB:         +3.47 V  (min =  +2.98 V, max =  +3.63 V)
> Vbat:         +3.38 V  (min =  +2.70 V, max =  +3.30 V)  ALARM
> fan1:        1288 RPM  (min =    0 RPM, div = 8)  ALARM
> fan2:        4218 RPM  (min =    0 RPM, div = 8)  ALARM
> fan3:           0 RPM  (min =    0 RPM, div = 128)
> SYSTIN:       +28.0°C  (high =  +0.0°C, hyst =  +0.0°C)  ALARM  sensor =
> thermistor
> CPUTIN:       +36.0°C  (high = +80.0°C, hyst = +75.0°C)  sensor =
> thermistor
> AUXTIN:      +110.0°C  (high = +114.0°C, hyst = +114.0°C)  sensor =
> thermistor
> cpu0_vid:    +0.450 V
> 
> Using the bios values as a reference, it appears that only one of the
> chassis fans and the CPU fan is displayed by SENSORS. Also moving one of
> the chassis fan plugs into the open CHA_FAN3 plug does not change the 0
> RPM value shown by SENSORS. And, with both chassis fans unplugged,
> (CHA_FAN1, CHA_FAN2, and CHA_FAN3 all open) SENSORS continues to show
> ~4200 rpm for fan2.
> 

The NCT6775F only has four fan sensors, and the last one is multiplexed
with the FDD interface (which would explain why you only see three
fans). Essentially, this means that the board must have another means to
monitor and/or control the other fans.

One question is if the CHA_FAN3 speed is shown in the BIOS if you
connect a fan to it. If so, I suspect that CHA_FAN2, CHA_FAN3 and the
power fan are controlled by the second chip (or maybe CHA_FAN[1-3],
since those can only be configured in the BIOS for either manual mode or
"full on").

I don't find any information on the web suggesting how the three
"missing" fans are controlled. Without that information, I don't think
there is anything we can do.

Guenter






More information about the lm-sensors mailing list