Replacing the power supply fan

I have a coolermaster power supply and the fan has locked up. It is a 120mmx25mm fan with a two pin connector. the only 120mm fans I can find are four pin connectors. Can I use the four pin connector with the two pins on the ps board?
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  1. Read this thread if you can find a fan with a 3-pin connector (lots of fans provide 3 and 4 pin connectors):

    If you can't find one or if the 3 pin connector won't fit, then you'll have to cut and splice the old cable connector and use only the ground and the 12volt wires.
  2. 3-pin fans normally have their wires color coded as:
    Pin 1 - Black - Ground
    Pin 2 - Red - +12VDC (varies for speed control)
    Pin 3 - Yellow - Speed pulse signal generated in the fan motor and sent back out to the mobo

    4-pin fans normally have their wires color coded as:
    Pin 1 - Black - Ground
    Pin 2 - Yellow - +12VDC (constant)
    Pin 3 - Green - Speed pulse signal generated in the fan motor and sent back out to the mobo
    Pin 4 - Blue - PWM signal from mobo to fan.

    Note that BOTH fan types have a little channel on the side on the connector near Pins 1-3 that matches up with a tongue on the male mobo fan connector. This ensures that the connectors only go together one way. But it is set up that Pin 1 is ALWAYS the one at one end where the groove is, and ALWAYS has a Black wire for Ground. The next one, Pin 2, no matter which fan type or wire color, is ALWAYS the +12 VDC line. To use any fan inside a PSU, you will only need to connect those two wires. The Speed Pulse wire and the PWM wire are NOT connected inside a PSU. (See one exception below.) NOT connecting these last two is not any problem. With the exception noted below, nobody cares about the speed of the PSU's fan. And a 4-pin fan is set up so that, if it gets the +12 VDC supply but NO PWM signal, it will simply run at full speed. In that situation if it gets a variable +VDC supply, that will accomplish speed variations of the fan.

    Inside your PSU, the old fan may well have black and red wires, and it is likely they are color coded the same - Black for Ground, Red for +12 VDC. So you can solder in your replacement fan that way. BUT just to be sure, look closely art the fan casing for two arrows. One will point through the fan to show the direction of air flow. The other will point around the fan to show the direction or blade rotation. Be sure to find out which way your old fan was mounted - blowing air into or out of the PSU - and mount your new one the same way. When you have finished the whole job and first turn on the power, check immediately which way the fan is turning, and whether it is blowing the right way. If not, you can simply re-do the solder job connecting the fan's two power lead to the PSU board, reversing them. Wiring it backwards will not harm the fan, but it will make it turn the wrong way. So if that happened, re-wire it the right way.

    Exception note: Some PSU's have a set of wires coming out of them that look just like a fan wire set, and have a connector on the end just like a cooling fan's. It is intended to plug into the mobo port labelled "PSU_FAN". Its function is solely to connect the Speed Pulse wire from the fan motor to the mobo so it can verify the PSU fan's speed. The mobo does not actually provide power to the PSU fan nor control its speed. But if your PSU and mob have this system, then you should connect the Speed Pulse line from the new replacement fan to this connector.
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