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  1. #1
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    Desperate for help (computer fan control) or this could cost huge $$$

    I am in desperate need of help, I have an extremely expensive motherboard and CPU, I think there may be a fault in the systems bios that has not been fixed yet but I think it may have already killed an AMD Threadripper 2950X.
    {Edited should have mentioned the Fan is four wire Noctua NF-A15PWM DC12V 0.13A}
    Everything seemed fine after the replacement but then five weeks later it happened again, luckily I saw it and was sitting in front of the computer at the time.

    The fan speeds have been set in bios with a minimum of 600 rpm so it should never just stop no matter what, I have had to remove the fan monitoring software from the desktop that came with the motherboard because it is definitely faulty and causes the computer to do a hard power down without warning. No this is not an emergency thermal shutdown as the CPU measured both by itself and through a probe were only 38.c

    When it first died I noted that the fan had gone off and the CPU's heatsink was hot enough to fry an egg on.

    I have seen an example circuit here https://www.instructables.com/id/Rea...-With-Arduino/ on how to read the fan speed but I would also like to determine if the signal saying stop is coming from the motherboard.

    I understand digital logic but nothing about how this fan stuff works, what I need is something that takes the 4 pin input from the motherboard and feeds that as per normal to the fan but pinches the reading off of it to determine what the motherboard is telling the fan to do and if it is telling it to go to zero sound a permanent alarm, or if the fan itself stops regardless of the fact the motherboard is sending the correct values to sound a different permanent alarm.

    I don't dare run this machine for to long without some sort of warning and it is scaring the carp out of me.

    I have an Arduino which I can use for this too.

    Hopefully someone can help.
    Last edited by 1stFalloutBoy; 13th October 2019 at 04:43.

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  2. #2
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    Re: Desperate for help or this could cost me a huge amount of $$$

    So what would be the downside of just replacing the
    fan's power source with direct +12V, presuming these
    are the usual sort of brushless fan, only fed a controlled
    voltage? Noise, power consumption, I think these are
    "don't care" (fans are single digit watts, you probably
    run a 500W power supply, are you really going to quibble?).

    The reason for all this fanciness is so the mfr can get
    some EnergyStar or similar merit badge. You might well
    not care, and just choose to go b@lls out on cooling,
    full time.

    PCs used to be that way.



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  3. #3
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    Re: Desperate for help or this could cost me a huge amount of $$$

    Quote Originally Posted by dick_freebird View Post
    So what would be the downside of just replacing the
    fan's power source with direct +12V, presuming these
    are the usual sort of brushless fan, only fed a controlled
    voltage? Noise, power consumption, I think these are
    "don't care" (fans are single digit watts, you probably
    run a 500W power supply, are you really going to quibble?).

    The reason for all this fanciness is so the mfr can get
    some EnergyStar or similar merit badge. You might well
    not care, and just choose to go b@lls out on cooling,
    full time.

    PCs used to be that way.
    Well it while it solves the problem, it doesn't point in any way to what the problem is which is what I am trying to figure out.



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  4. #4
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    Re: Desperate for help (computer fan control) or this could cost huge $$$

    Quote Originally Posted by 1stFalloutBoy View Post
    I would also like to determine if the signal saying stop is coming from the motherboard.
    ...
    or if the fan itself stops regardless of the fact the motherboard is sending the correct values
    To know what's going on you must monitor several readings. You need to know what volt levels go to the fan. You must confirm temperature of the device (or more than one device) that causes the fan to turn on or off. It's a matter of setting up a laboratory around your computer, as it goes through many sessions of operation. Watching readings as it heats up, and as it cools down.

    It's important to determine whether the problem is in the fan or the motherboard. I'd expect to spend several hours running one of them apart from the other.

    Discover what the fan does under what conditions of temperature, or supply voltage, etc.

    Discover how hot the motherboard gets in order for it to send a 'turn on fan' signal. Discover how cool it gets in order to send an 'Off' signal.

    Direct a plain fan toward it to see what range of temperature you get from the onboard sensor. It's hard to be sure whether the enclosure needs to be in place while the computer is on. The enclosure may be designed to enhance air movement so it cools better.

    Ideally I'd compare results with an identical new fan, in case my fan is faulty.

    To tell the truth, I suspect I'd eventually break something on my expensive motherboard. And I'd say 'Why couldn't I leave well enough alone?' (which I've asked myself more than once in the past).

    If you think the fault may be in the system bios, then an update may be available. You can see how involved all this gets.

    It may be easier (per post #2) to install a different fan, or auxiliary fan.
    Assume the fan is needed all the time the computer is turned on, and adjust its speed accordingly.



  5. #5
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    Re: Desperate for help (computer fan control) or this could cost huge $$$

    Quote Originally Posted by BradtheRad View Post
    To know what's going on you must monitor several readings. You need to know what volt levels go to the fan. You must confirm temperature of the device (or more than one device) that causes the fan to turn on or off. It's a matter of setting up a laboratory around your computer, as it goes through many sessions of operation. Watching readings as it heats up, and as it cools down.

    It's important to determine whether the problem is in the fan or the motherboard. I'd expect to spend several hours running one of them apart from the other.

    Discover what the fan does under what conditions of temperature, or supply voltage, etc.

    Discover how hot the motherboard gets in order for it to send a 'turn on fan' signal. Discover how cool it gets in order to send an 'Off' signal.

    Direct a plain fan toward it to see what range of temperature you get from the onboard sensor. It's hard to be sure whether the enclosure needs to be in place while the computer is on. The enclosure may be designed to enhance air movement so it cools better.

    Ideally I'd compare results with an identical new fan, in case my fan is faulty.

    To tell the truth, I suspect I'd eventually break something on my expensive motherboard. And I'd say 'Why couldn't I leave well enough alone?' (which I've asked myself more than once in the past).

    If you think the fault may be in the system bios, then an update may be available. You can see how involved all this gets.

    It may be easier (per post #2) to install a different fan, or auxiliary fan.
    Assume the fan is needed all the time the computer is turned on, and adjust its speed accordingly.
    All I need to know in this instance is what the motherboard is feeding out to the fan as a measurement and what the fan is reporting as it's speed as a measurement, that is all, once I know that I am sure I can figure the rest out.



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  6. #6
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    Re: Desperate for help (computer fan control) or this could cost huge $$$

    Hi,
    All I need to know in this instance is what the motherboard is feeding out to the fan as a measurement and what the fan is reporting as it's speed as a measurement, that is all, once I know that I am sure I can figure the rest out.
    Did you do an internet search?

    https://en.m.wikipedia.org/wiki/Computer_fan_control

    Klaus
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    Re: Desperate for help (computer fan control) or this could cost huge $$$

    Quote Originally Posted by KlausST View Post
    Hi,

    Did you do an internet search?

    https://en.m.wikipedia.org/wiki/Computer_fan_control

    Klaus
    Hi, I am aware of the specifications for the pinouts of fans what I don't know is how to read the Signal from the motherboard that tells the fan what to do, I have no idea what the signal looks like and no idea how to interface that signal to the Arduino, I have seen a circuit for reading the fan RPM from the fan and that looks simple enough, one resistor involved.



  8. #8
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    Re: Desperate for help (computer fan control) or this could cost huge $$$

    Hi,

    I have seen a circuit for reading the fan RPM from the fan and that looks simple enough, one resistor involved.
    Did you read the WIKIPEDA article.

    It says it delivers 2 pulses per revolution.
    That's all you need.
    Measure/calculate the count of pulses per minute and divide it by 2 ... and you are done.
    ... then a simple resistor could do the job to limit current in case the signal voltage is higher than Arduino's clamping voltage.

    ***

    The same you can do with the PWM signal. Just measure the duty cycle.

    Klaus

    Btw: Usually the motherboard contains all that is necessary to monitor the RPM of the fan.
    Maybe you just need to do the correct setup in BIOS and/or use a utility PC software.
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