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Thread: Can't "Stop" my CPU Fan ?

  1. #1
    Join Date
    Jul 2012
    Xubuntu 16.04 Xenial Xerus

    Question Can't "Stop" my CPU Fan ?

    OK, before you all go, why would you want to, this is about getting full control over my fans on my new system. I have got so far with it but this last bit is niggling me.


    Asus Z87M PLUS motherboard (with Q Fan Control)
    Intel i5 4670K processor
    CPU Cooler: TITAN TTC-NK35TZ/RPW/V3 (
    Nvidia GTX 650
    4gb ram
    128gb SSD

    Xubuntu 12.04.3
    sensors detected: coretemp nct6775

    lm-sensors installed, pwmconfig run and fancontrol in place with a config file

    # Configuration file generated by pwmconfig, changes will be lost
    # FAN1 is Chassis Fan  #  FAN2 is CPU Fan
    DEVPATH=hwmon0= hwmon2=devices/platform/nct6775.656
    DEVNAME=hwmon0=acpitz hwmon2=nct6791
    FCTEMPS=hwmon2/device/pwm1=hwmon0/temp1_input hwmon2/device/pwm2=hwmon0/temp2_input
    #                CHASSIS FAN                                                    CPU FAN
    FCFANS=hwmon2/device/pwm1=hwmon2/device/fan1_input hwmon2/device/pwm2=hwmon2/device/fan2_input
    #             CHASSIS                            CPU
    MINTEMP=hwmon2/device/pwm1=35 hwmon2/device/pwm2=35
    MAXTEMP=hwmon2/device/pwm1=80 hwmon2/device/pwm2=70
    MINSTART=hwmon2/device/pwm1=90 hwmon2/device/pwm2=50
    MINSTOP=hwmon2/device/pwm1=59 hwmon2/device/pwm2=10
    After disabling fancontrol (gets noisy!) I have been sending pwm changes to each of the fans like so

    echo 100 > /sys/class/hwmon/hwmon2/device/pwm2
    using values to echo between 0 and 255. For the case fan (3 pin!), I found the fan would stop at 59 and restart at 90, so set those values. Nice and quiet

    However I can put 0 in for the CPU fan (4 pin) and the fan speed will only drop to @ 1300 rpm (top speed = 2700rpm), it won't stop as it should.

    CPU at idle is only @ 29 degrees C.

    I have been into the bios and set up the CPU fan as manual with a temp range of 40 and 70 degrees for testing

    My target is to reduce the CPU fan speed to @ 750rpm at idle and have the case fan running slowly all the time.

    I must be missing something......
    Last edited by Merrattic; September 1st, 2013 at 03:38 PM.
    The best things in life are free, so what are we paying for?

  2. #2
    Join Date
    Jan 2006
    Sunny Southend-on-Sea
    Ubuntu 14.04 Trusty Tahr

    Re: Can't "Stop" my CPU Fan ?

    It's fairly common for CPU fans not to turn off. Sometimes it's the fan, most times it's the controller. You might have another 4-pin connector for a case fan that doesn't have that restriction, or you could use a fan that's sufficiently quiet at half speed.
    None but ourselves can free our minds

  3. #3
    Join Date
    Jul 2012
    Xubuntu 16.04 Xenial Xerus

    Re: Can't "Stop" my CPU Fan ?

    Thanks, I was thinking it was something along those lines. I have a second 4 pin connector for a case fan, might give that a go sometime (once the warranty runs out!)
    The best things in life are free, so what are we paying for?

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