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Running 80mm case fan off the CPU fan?

Discussion in 'Cases, Modding & Electronics' started by Alcpone, Feb 13, 2013.

  1. Alcpone New Member

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    For some reason I can't control the speed of my case fan that is connectecd directly to the sys fan on my mobo, it is at full speed all the time and I cant control it with speed fan or the like, can I splice it into the cpu fan so it speeds up and slows down with that?
  2. Jetster

    Jetster

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    Did you try the BIOS to set the speed? Its probably not thermally controlled but most MB have a speed setting. Did you install cool and quite?
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  3. xvi

    xvi

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    I have NEVER had SpeedFan work for me. Try downloading AMD Overdrive.

    I would be careful with how much amperage you pull off of one fan header. If you don't want it running at full speed, I would do one of three things. One, buy/make/find an adapter to run the fan off of 5v from a 4-pin molex connector. Two, buy a fan controller. Three, buy a lower power fan to replace it.

    If you do try to splice it in to the CPU fan, make sure to omit the yellow wire. That's the tach.
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    Crunching for Team TPU 1 Million points folded for TPU
  4. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    Speedfan is a dying piece of software. I have never had it work for me either, even on P4 machines. The best thing for fan control is a bay controller. Yes the CPU fan header will work but what do you have your CPU cooler plugged into?
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  5. newtekie1

    newtekie1 Semi-Retired Folder

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    Your CPU fan is likely speed controlled via PWM(4-wires) while your case fan is probably not PWM controllable(3-wires). So even if you did splice them together, the case fan would still likely run at 100% all the time.

    Also, the SYS_FAN1 header on your motherboard is a PWM header as well, so if you have 3-pin fan connected to it the header won't be able to control the speed. So the solution would be to buy a 4-pin PWM Case fan to replace the current 80mm case fan.

    This should do the trick: GELID Solutions FN-PX08-20 Case Fan - Newegg.com
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  6. Alcpone New Member

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    Ok thanks for the replies. It is only a 3 wire fan and the sys fan has only 3 pins so not sure if the sys fan does have pwm or not? I thought the the speed was governed by home much power the mobo was giving it?
  7. Jstn7477

    Jstn7477

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    The board has 4 headers from what I see: CPU_FAN (PWM), PWR_FAN (DC, top right, probably fixed at 100%), SYS_FAN (PWM, bottom right, probably adjustable) and SYS_FAN2 (DC, bottom edge, likely fixed at 100%). Most boards under $100 only have one or two controllable headers, and PWR_FAN is usually fixed at 12v on most boards.
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  8. Alcpone New Member

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    I will try a different header. Cheers
  9. Alcpone New Member

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    Turns out I had it plugged into the pwr fan header, oops. Tried in the sys fan header and it works a treat, only problem I have is it is too short to reach, typical. I will have to get some wire or splice it into the cpu fan.
  10. AsRock

    AsRock TPU addict

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    Make sure it's not a very high ampage fan too like some delta fans are as a lot of mobo headers only can take so much drain on them.
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  11. Alcpone New Member

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    All sorted now. Thanks
  12. cadaveca

    cadaveca My name is Dave

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    1A total or less, depending on board model.
  13. de.das.dude

    de.das.dude Pro Indian Modder

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    speedfan sux :p

    the best way to control is to get a cheap controller
  14. Geofrancis

    Geofrancis

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    If you get a 4 pin PWM case fan you can attach the 4th PWM wire to the CPU fans PWM wire and it will be controlled with the CPU even with the fan plugged onto a 3 pin header.
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