12volt to 5volt

Discussion in 'Modding' started by Opti, May 10, 2005.

  1. Opti

    Opti Member

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    Isn't there a way to make your 12v case fan 5v, or 7v i think to slow it down, by changing the wires some how? I'm sure i seen it somewhere but dunno where.
     
    Last edited: May 10, 2005
  2. aln

    aln Member

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  3. OP
    OP
    Opti

    Opti Member

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  4. hendot

    hendot Member

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    you can do it without cutting or soldering wires. Just de-pin a molex connector (even just the red and yellow pins) and switch red and yellow. Seeing as you are only doing 2 pins, it isn't too tedious to just use a needle to do this.
     
  5. aln

    aln Member

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    yea...you can...but i don't have anything to depin them...and don't know how...
    you can also make a 7v mod by crossing one of the black wires with the red
     
  6. dakiller

    dakiller (Oscillating & Impeding)

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    after connecting 5->12 it's probably better to not connect the 12 to the 5 and only have 1 ground wire as well, so its sort of a visual reminder that its for fans only as if you mistake it for a normal one and connect to something you shouldnt Bad Things will happen
     
  7. OP
    OP
    Opti

    Opti Member

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    what is the fan has only one red wire and one black wire? Can't do it? Also if your running two fans together and they are wired together, they will still be running at 12volt yeah?
     
  8. petercr

    petercr Member

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    If the fan only has two wires, it will still work. The red is +ve and the black is -ve (or ground). The third wire (usually yellow) is used for the speed sensor and is generally left connected directly as it goes back to the motherboard header and in theory this is the only wire that needs to be connectored for the speed to be measured. As to the two fans, it depends on how they're wired up - if they're in series (ie black wire of one is connected to the red wire of the next) then you need 2x the rated voltage of the fans to drive them at their rated output. If they're in parallel (red to red and black to black) then you'll need to supply the combined current rating of the two fans.
     
  9. phathag

    phathag Member

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    this site is what i am about to use to de-volt my loud case fans...

    http://www.7volts.com/

    i believe most of the time people would go to 7volts from 12v as 5v sometimes is not enough to start the fan... so ive read.
     
  10. Kenny12

    Kenny12 Member

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    just use a little screw driver / toothpick to depin them easy as
     
  11. OP
    OP
    Opti

    Opti Member

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    to depin the male connectors just get some 5/32" od nylon air hose, you get it from a truck parts place, it fits over the male pin and you can push the tabs in. You only need about 3inchs of the stuff.
     
  12. SteakTheMooCow

    SteakTheMooCow (Taking a Break)

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    Ok, what everyone has NEGLECTED to mention is this:

    You need to find the bits that stick out (usually 2 of them). Depress that with a small object (eg. precision screwdriver). Once you've done this the pin usually falls out of place. Then just bend them back up (GENTLY!) and stick them back where you want them.
     
  13. Lucanus

    Lucanus Member

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    As someone said earlier - Be careful not to connect anything other than fans after the converter. I'm ashamed to say it, but I once blew up a brand spanking new (and at the time *very* expensive) 18.2gig Quantum Atlas 10K U160 SCSI disk that way. :o
     
  14. SteakTheMooCow

    SteakTheMooCow (Taking a Break)

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    If the fan has a 4 pin running through it F-> just swap the pins again and you can plug anything in... just remember to fix it up :)

    Oh, and make sure you change it on the MALE side, otherwise you'll still have a damn fast fan =\
     
  15. montyt

    montyt Member

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    i find that it is safer to modify the connector on the fanso that way you dont blow anthing up, and you are only modifying the fan voltage and not anything after the fan.

    please be aware that not all fans will run at 5 volts.
    some will not have enough power to start.

    i run my fans at 7 wolt.
    keep + wire connected to yellow (12 volt)
    and disconnect the black wire (ground wire) and connect the ground wire to red wire (5 volts)
     
  16. SteakTheMooCow

    SteakTheMooCow (Taking a Break)

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    ...

    ok, heres how to do it CHEAPLY WITHOUT blowing anything up.

    [​IMG]

    note: green replaced yellow for clarity.

    Molex 1 (on the left) you leave alone. (assume it comes from the PSU)

    Molex 2 (the fan molex): you swap the yellow (in the diagram in green) with the black cable which is under the red.

    Molex 3 (the other fan molex): you swap the yellow with the black again.

    I've done it, it works... :: shrugs :: no cutting, just pop out the molex with a precision screw driver, needle or something else tiny.
     
    Last edited: May 11, 2005
  17. metamorphosis

    metamorphosis Member

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    Works fine for my 12" evercool but yeah some fans don't cut it, in that regard-
     
  18. Sephir0th

    Sephir0th Member

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    or, rather than change two lots of wiring, all i did was get one of the 3-4pin fan adapters, get a knife and expose some of the red 5v wire, cut the black wire that goes from the molex to the fan header away from the black molex wire and solder it onto the red 5v wire, then put electrical tape over the exposed wires, easy.

    and also your diagram is very wrong, you say green=yellow in the picture, you have red (5v) going to the fan +, and green(yellow=12v) to the fan - which would give -5v to the fan. Just thought i'd clear that up
     
  19. jrun4117

    jrun4117 Member

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    Does having the fan connecting across 12V and 5V mean that the PSU has less control over voltage levels because a sudden current draw (surge) on the 12V or 5V can now affect both rails?
     
  20. SteakTheMooCow

    SteakTheMooCow (Taking a Break)

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    ah true seph...

    red = yellow
    green = red :p

    edit: but I have a 5V fan?
     
    Last edited: May 11, 2005

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