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CPU Fan Stuck on Maximum

Discussion in 'Overclocking' started by Justin, Nov 7, 2004.

  1. Justin

    Justin Guest

    I just got a Thermaltake Polo735 which comes with a speed controller.
    Initially the controler slowed the fan down a little but it was
    intermitant. Now the fan is stuck on full speed - and is bloody noisy.
    The fan was originaly attached diectly to the PSU. I have made a
    slight mod and have it now connected the the fan pins on the
    motherboard. The fan controler still makes no diffrence with the fan
    stuck on full speed. Does it just sound like a flakey fan and should I
    send the fan back for a replacement? Does any one have experience with
    refunds(in Australia)?

    Justin
     
    Justin, Nov 7, 2004
    #1
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  2. Justin

    Overlord Guest

    Perhaps the fan controller simply went out. 99.9% of CPU fans will slow
    down given lower voltage. The chances of a bad fan not slowing down,
    or stopping due to lower voltage from the motherboard are very low.

    In any case, I would first check the temps of the CPU.
    Perhaps the thing is so hot, in the BIOS worldview, there is no other speed.
    And speaking of the BIOS.... does it have, and have you used the settings
    in the BIOS for some measure of control of the CPU fan?

    I suppose it could be the motherboard but most boards I've seen with
    a blown fan header lose all voltage on the connector.


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    Overlord, Nov 8, 2004
    #2
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  3. Justin

    Justin Guest

    Initialy the fan controller made a diffrence - slowing things down,
    but not anymore. The fan came with 2 different dial controlers and
    both have no efect now.

    The CPU temp is comming up as 41 to about 45 degrees C.

    Maybe the actual mechanism in the fan going to the controler is
    shorting and keeping the fan on maxium?

    If I enable the CPU "smart fan control" in the bios this seems to clow
    things down a little - though the bios says if it is over 40 it will
    put the fan on maximum. The fan is now running at 4440 RPM.

    I don't think it is the motherboard as the fan is on max even when
    connected directly to the power supply and not via the motherboars.

    Justin

     
    Justin, Nov 10, 2004
    #3
  4. Justin

    Overlord Guest

    I suspect the fan controller crapped out.

    Since the CPU temp is above it's max fan speed, connected to the
    MB, the controller would be the only thing slowing it down, and it's not.

    More likely the external fan controller has shorted out across the pot.

    MB vs PS is as follows;

    Since the controller is shorted (tuner cleaner might - Might fix it),
    the only controlling influence on the fan is the MB. And since the
    CPU temps are so high, the MB isn't even trying to slow the fan.

    The standard connection to the PS is Going to run the fan at full speed.
    The PS is feeding the fan 12 volts. When connected to the MB (with the
    temps lower), the MB slows the fan by cutting the voltage going to it.

    Pull the fan controller and put a meter across it. it's shorted and not
    dropping the supply voltage to the fan. You can use tuner cleaner on/in
    it to possibly dislodge whatever is in it shorting it, or replace it. Depending
    on what is shorting it, you might possibly rewire it to make it work.

    Or, you can replace the fan with a quieter fan that will still run flat out.

    Or, replace the fan with a higher airflow fan. When the higher airflow cools
    the CPU below 40°C, the MB will finally slow the fan by cutting it's voltage back.

    Pull the heatsink, clean CPU and HS, carefully reapply thermal paste and
    reinstall the HS/fan. Better heat transfer to the heatsink will cool the CPU
    better and possibly drop the temps below the BIOS limit of 40°C so the MB
    will once again drop the fan voltage/speeds. Better case airflow will also
    help lower the CPU temps.

    If you just don't want to do these......
    You can hook the fan to the PS lines but crosswire them to produce 7 volts
    going to the CPU fan. It's not really reccommended for a CPU fan but if your
    sanity is in the balance......
    On the standard 4pin molex connector from the PS, the 2 black inner wires are
    grounds. The yellow wire is +12volts and the red wire is +5volts.
    Your ran sucks the yellow wire and a black ground for +12volts because the
    difference between +12 and 0 is +12volts.
    If you swap the wires on the connector for the fan so it sucks at the yellow and
    red wire, you will be running the fan at +7volts; the difference between
    +12 and +5 = +7volts.

    However it's not reccommended as some fans require the +12volt kick to start
    them spinning and your fan may not initially start at all. Also your present fan/
    HS/thermal paste is already struggling and still can't get below the 40°C limit.
    If the fan runs on +7volts from the PS, the temps aren't going anywhere but up.

    Quieter but very risky; your choice.


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    Overlord, Nov 10, 2004
    #4
  5. All this talk of the motherboard... I can't figure out how you've got it
    connected up.

    The instructions say there's one wire to the motherboard for RPM monitoring
    and if that's what you've done then it doesn't matter one bit what the
    motherboard 'smart fan control' does as the fan isn't connected to it.

    You can also only use one controller OR the temp sensor, not both.

    And, according to Thermaltake's spec sheet, maximum speed is 5500 RPM, not
    4400, so it isn't on max.
     
    David Maynard, Nov 10, 2004
    #5
  6. Justin

    Spajky Guest

    thats because of the RPM readings wire, solution on my site under
    electronics ...
    have to be taken also care (like I mentioned before) if wanna having
    RPM readings with 3wire fans ..
    the kick start problem is resolvable (also there on my site) & temps
    do not jump up very much if the air flow is decently made ...
     
    Spajky, Nov 12, 2004
    #6
  7. 1) Clean out the heatsink re fluff
    ---- particularly if the heatsink has thin-fins of tight density
    ---- airflow obstruction is & will be a major problem for laptop skived copper HSF
    2) Does sound like your fan controller is not working correctly
    ---- however it could also be the heatsink is no longer seated correctly

    You could try reversing the modification you have performed:
    o If the fan was powered by the PSU, was the PSU regulating fan rpm
    ---- specifically was the PSU temperature controlling the fan
    o If the fan is connected to the m/b, is the fan header working correctly
    ---- substituting another fan in its place may be a test worth doing

    If the machine cold-boots, and the fan is temperature controlled by the
    motherboard then it should start off at a lower setting. Might be worth
    checking the BIOS settings carefully, the heatsink fitment & other temp
    readings (using say MBM5 or other temperature utilities).
     
    Dorothy Bradbury, Nov 12, 2004
    #7
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