Question about fan connectors

By samjohnson
Aug 21, 2007
  1. Ok so I have a four pin fan connecter on my case fan and my motherboard is a three pin fan connector. Is there anyway to connect the four pin to the three pin?? If it makes any difference the connector for the fan is part of the power supply wires (if that makes sense). I don't actually have a connector that is on the fan. I have the PSU connector hooked to the fan and then there is a four pin connector that looks like it is the ones that you would hook into the motherboard but it is four instead of three. Thanks
  2. raybay

    raybay TS Evangelist Posts: 7,241   +9

    Why? Fans are dirt cheap. Why mess with them, and risk trouble, when you can buy another fan for $12
  3. mica3speedy

    mica3speedy TS Rookie Posts: 89

    or you can get a four pin to molex adaptor and hook the fan to your power supply
  4. Halos

    Halos TS Rookie Posts: 27

    I would go with raybay here and say that your best bet is getting a fan that's compatible with the motherboard. No electronic ever likes being converted. Compatibility is the key word to it all.
  5. raybay

    raybay TS Evangelist Posts: 7,241   +9

    But most places sell the molex to four-pin adapter for $5.95 or more... good money after bad.
  6. samjohnson

    samjohnson TS Maniac Topic Starter Posts: 238

    Ok guys thanks. I will probably just get another fan that can hook to the motherboard.
  7. pdyckman@comcas

    pdyckman@comcas TS Rookie Posts: 527

    Sometimes the 3 pin connector will slide onto the four pin outlet. There are two ridges that guide the connector into place. three pins are actually connecting. I've seen this many times. Try to (gently) assemble the two connectors and watch to see that three pins slide into the female connector. If you notice that the three input connector is not as wide as the four pin output then these may go together as described.
  8. raybay

    raybay TS Evangelist Posts: 7,241   +9

    Any such work based on assumptions is dangerous, potentially costly.
  9. AlbertLionheart

    AlbertLionheart TechSpot Chancellor Posts: 2,026

    I had always worked on the basis that 4 pin connectors were for speed (noise) control. Therefore plugging in a 3 pin fan is unlikely to work as it should. Raybay is right - don't mess with this and go the job properly!
  10. samjohnson

    samjohnson TS Maniac Topic Starter Posts: 238

    I think I will just get a fan with a three pin connector to plug into my motherboard. I dont want to end up messing my mobo up. Thanks guys for your help! :D
  11. Rilla927

    Rilla927 TS Rookie Posts: 152

  12. AlbertLionheart

    AlbertLionheart TechSpot Chancellor Posts: 2,026

    Sorry - if there is a 4 pin connector, get a fan with a 4 pin plug on it! NO messing and I really would not compromise the cooling. Without it you may find the incorrect fan runs flat out all the time and makes too much noise!
  13. Rilla927

    Rilla927 TS Rookie Posts: 152

    Ya, but that what the adapters are for (to modify). No need to to buy another fan or compromise cooling.
  14. AlbertLionheart

    AlbertLionheart TechSpot Chancellor Posts: 2,026

    Ask the guys who sell the adapters if they care what they are used for!
  15. Rilla927

    Rilla927 TS Rookie Posts: 152

    Are you telling me you have never modified anything in any way what so ever on a computer before?
  16. AlbertLionheart

    AlbertLionheart TechSpot Chancellor Posts: 2,026

    Nope - when I was young and foolish (I am now older and still foolish) I did all sorts of awful things, especially to computers, and paid for it with hard earned cash. I have trashed perfectly good boards and chips by overclocking, overheating and generally buggering them about. See an empty slot - shove some RAM in it - see an idle connector - stick a drive on it whether I needed it or not. The I wondered why the thing behaved like a snail on Lebanese Gold.
    I would not listen to those who had gone before and made the same silly mistakes. Don't do it, they said, because it will break: and they were right.
    Told you.
  17. samjohnson

    samjohnson TS Maniac Topic Starter Posts: 238

    Ya I agree with Albertlionheart, I don't want to do something that may screw my comp up. I just put this computer together a couple of months ago and don't really have any money to go and replace somthing right now. I need to get a better fan anyway so I will go that rout. :D
  18. DeepMartin

    DeepMartin TS Rookie Posts: 54

    speaking of the devil i just plugged a two cable fan to the 2nd system fan mobo now i wonder if its a big no no
    cuz now m thinking without the third cable the mobo has no control of the speed of the fan right?
  19. KingCody

    KingCody TS Evangelist Posts: 992   +8

    4-pin fans are PWM fans. the first 3 pins/wires are the same as a standard 3-pin fan, the 4th pin/wire is the 'pulse' wire for PWM speed control. you can plug a 4-pin fan into a 3-pin motherboard fan header, but speed control will be lost. depending on the fan, some will run at maximum speed, others will run at minimum speed.

    you can also use a 3-pin fan with a 4-pin motherboard fan header. same as above the first 3 pins/wires are the same as a standard 3-pin motherboard fan header, the 4th pin is the 'pulse' wire for PWN speed control. using a 3-pin fan poses no danger or loss of functionality. it will simply run at full speed, just as it would if it were plugged into a standard 3-pin motherboard fan header.

    both '4-pin' examples above are in reference to a 4-pin PWM fan connector (looks just like a regular 3-pin fan connector but with an extra pin/wire). some fans have a 4-pin molex connector (same power connector used for PATA hard drives and CD/DVD drives). these connectors do not plug into the motherboard, but directly into the power supply. even though the connector has 4 pins, only 2 of them are actually used. this type is equivalent to a 2-pin fan connector and should not be confused with a 4-pin PWM connector.
    NOTE: the 2 pictures used above were taken from

    wrong. the third wire (usually yellow) on a 3-pin fan connector is only to monitor fan speed (it doesn't control fan speed, it only monitors it). the other two wires (usually red and black) are the same as a 2-pin fan connector. you can use a 2-pin fan with a 3-pin or 4-pin motherboard fan header as long as they are connected to the proper two pins (+12v and ground).

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