p870tm 2nd CPU fan port!

Discussion in 'Sager and Clevo' started by tanzmeister, Jan 9, 2018.

  1. ole!!!

    ole!!! Notebook Prophet

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    in this case i think it'll work just fine we if power it off primary 12v pin. 2nd cpu fan will just be at w/e voltage primary cpu fan runs at and both be controlled. i'll try grabbing two fans and test what is the maximum output of that pin if its 0.7A. (how did you figure out 0.7A btw?)

    a 0.24A, 0.15A and 0.1A 12v fans would work for these i'll try splitter them.
     
  2. poprostujakub

    poprostujakub Notebook Consultant

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    "Output current limit" section:
    12v.PNG
     
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  3. ole!!!

    ole!!! Notebook Prophet

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    in this table, with current short circuit protection at 0.2A, does that mean we got 0.2A more room to work with ontop of 0.7?
     
  4. poprostujakub

    poprostujakub Notebook Consultant

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    No, it means, that after short circuit protection is triggered, IC will start limiting output current to 0,2A max. With this limit fan will still works, but with much lower speed. If IC recovery procedure after fault will again trigger SCP, cycle will looped and fan will be continously switched between normal speed and clamped speed.
     
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  5. Danishblunt

    Danishblunt Guest

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    Can confirm this.

    Also I would strongly advice not to run it on amp limit unless you feel like trying to break something.
     
  6. ole!!!

    ole!!! Notebook Prophet

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    would a shutdown/restart break this cycle? (i'd assume so)

    i'll get something with theoretical value of say .15A + original CPU fan of .5A. combine the two, run them with FN+1 and see if i can get this triggered, if not i'll go up a tier .19A and then .24A fans.

    my understanding is even though the fan is rated at .5A it might not draw .5A even at 100%, some might be +/- 5 to 10% or some might draw less than what its specified., no way to know until fan combination are tested.
     
    Last edited: Feb 23, 2018
  7. poprostujakub

    poprostujakub Notebook Consultant

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    Only way to figure out real behavior is checking this in practis.
    Your method looks good, I'm waiting for results.
    In my experience most of fans draws significantly less current than producer declares on label (e.g. 5V/0,5A fan from Clevo D870 draws 0,33A at full speed), so there's a big chance than second fan will work without any problems.
     
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  8. Meaker@Sager

    Meaker@Sager Company Representative

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    If you stick to ratings everything should be designed with some tolerance. The further you stray the more you will have to manually watch values.
     
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  9. poprostujakub

    poprostujakub Notebook Consultant

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    It's true. For mass production designers assumes typical values in their projecs. But if enthusiast in his home is ready to spent a lot of time on testing solutions, there's possibility to achieve results much better than in regular device. Simple example - extreme overclockers. They selects processors, mainboards, powers supplies to achieve results far beyond regular user capabilites.
     
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  10. ole!!!

    ole!!! Notebook Prophet

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    time to order the 12v fan boys (pun intended), i'll let you guys know how it goes once i got fans and splitter. fans are from china so this could take awhile.
     
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