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PWM and DC fans

I have an asus z170 deluxe motherboard and am looking to control 3 DC 3pin fans and 8 PWM 4 pin fans. In the bios there is an option to choose DC or PWM but is it possible set it to PWM and still connect the 3 DC 3pin fans or will they not work properly
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  1. If that board has 4 x 4-pin headers, that only allows you to use the 8 x PWM fans safely. Normally, one does not use more than 2 fans per header due to the current rating for the header. If I were you and wanted that many fans in my case, I would look into a fan controller that mounts in one of the unused external drive bays.
    http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=pwm+fan+controller&N=-1&isNodeId=1
  2. clutchc said:
    If that board has 4 x 4-pin headers, that only allows you to use the 8 x PWM fans safely. Normally, one does not use more than 2 fans per header due to the current rating for the header. If I were you and wanted that many fans in my case, I would look into a fan controller that mounts in one of the unused external drive bays.
    http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=pwm+fan+controller&N=-1&isNodeId=1


    I cant use a fan controller because the case has no external drive bays and then wouldn't ramp the fans up and down depending on temperature of multiple different components. and I think the fan controllers look hideous. This is not the worry anyway. The PWM fans are the corsair mag lev 120 fans and the DC are the corsair sp120 rgb so can easily fit 3 on one header, which I have 5 case fan headers and 2 cpu headers and then a separate dedicated header for the pump. The problem I am unsure about is if I set the bios to PWM will the 3 DC fans work correctly
  3. Best answer
    Normally 3-wire fans aren't speed-controllable on a PWM header. But that isn't always the case. It is dependent on the BIOS/Board manufacturer. Most boards I've built with didn't allow it, but a few of the higher end boards I've used have allowed it. You'll have to test it yourself, unless someone that has that board jumps in with a conclusive answer. Or maybe contact Asus.

    Good luck with 3 fans per header. Don't forget that locked-rotor (starting) current is always momentarily much higher than the rated running current on the fan motor nameplate.
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