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Wiring 80mm fan to 3850 fan header

Discussion in 'Graphics Cards' started by KainXS, Jan 7, 2008.

  1. KainXS

    KainXS

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    A friend of mine was having temp problems with his card so we came up with the idea of wiring an 80mm fan to the card and it dropped his temps but I'm wondering if you can wire a 80mm fan to be controlled by the 3850 via the fan header on the card, the 80mm fan is a thermaltake with a molex 4 pin on it

    this is the card

    [​IMG]
     
  2. pbmaster

    pbmaster New Member

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    You might be able to but I doubt it...that 80 mm takes much more power than that small fan on the card itself. Also, you would have to fabricate some kind of connector to join the two together.
     
  3. Silverel

    Silverel New Member

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    Nerp. Gonna need a fan with a 3rd wire on it, otherwise you'll need something like a rheostat to control the speeds. The third wire usually controls the fan speed, or at least reports the voltage to the board, which would then control the fan speed.

    I wouldn't recommend using the header on a videocard anyways if you have the option to use a molex connector. I just recently pulled the fan off my 9600pro and replaced it with a 60mm, then stuck that wire to the mobo chassis 3-pin fan connector. Unfortunately for me the 9600pro doesn't have a temp sensor, otherwise I could set up an automatic throttling for 2d->3d useage. For now I do it manually.
     
  4. KainXS

    KainXS

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    So it would be better to leave it running off the molex
     
  5. Silverel

    Silverel New Member

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    Right.

    Even if you got it wired to the card itself, it still wouldn't allow you to control the fan speed with only the two wires coming off the fan. Or it might, but once it goes below a certain point, the fan would shut off instead of going slower. That point should be where it would transition from 12v current (which your fan uses on 2 wires) to 5v current which is the extra two headers on your board. They might be 3.3v headers though... point being, two wires aren't gonna get the job done for ya.
     
  6. keakar

    keakar

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    nice little mod idea though, figured i would see more mods like this rather than see people spending $ on expensive aftermarket coolers. its sad that most people never consider modding things like this instead of spending $.

    can you tell us the temps before and after this fan mod? and have you tried other fans (higher or lower cfm) ?
     
  7. KainXS

    KainXS

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    we tried an overvolted 92mm fan and it was very effective, temps dropped from 46 idle and 80+ full load to about 28C idle and 59C full load
    with the 80mm fan the idle temp is about 35C and load is about 67C

    the card is at the 3870's voltage also
     
  8. trog100 New Member

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    the 3870 runs at the temps it does cos ati have it set to target 90 C.. the cooler is well up to keeping the card at lower temps.. if u dont mind the fan running a fixed speed all the time use riva tuner to set it at about 60%.. it will run very cool then..
    if u like the sound of leaf blowers set it at 100 C.. see how cool the card runs then.. he he he

    trog
     
  9. TonyStark

    TonyStark New Member

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    A better solution is to turn up fan speeds in ATI Tool or RivaTuner, or flash a BIOS with modded fan speeds.....
     
  10. erocker

    erocker Super Moderator Staff Member

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    I hope you have both fans running!? I like it.:D
     
  11. trog100 New Member

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    please tony.. tell me u have actually found one as opposed to simply assuming such a thing exists.. ???

    a bios that targets 75 C instead of 90 is my dream..

    i have found one thing out thow.. push the card temps to 102 C (more voltage to the gpu) and the lazy stock fan wakes up and runs 75% with a fair bit of noise instead of its leisurely 40 % which comes in at 92 C

    and just for interest.. with just a wee bit more voltage to the gpu than stock.. my stock fan now runs at 50% in its attempt to maintain 90 C-sh..

    trog
     

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