# Fans not working.



## JamesBwoii (Dec 19, 2010)

I just got a new molex to 3pin fan cable and tried it out straight away. On connecting 2 fans to it I noticed it didn't work. I then tried a fan which I knew worked and still nothing. I then noticed that where one of my fans plugs into the motherboard there are 3 metal pins, but on this adapter there are only 2 - is this why it doesn't work?


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## gcavan (Aug 13, 2009)

I expect something else is wrong. The third pin is for RPM feedback sense (so the motherboard may read the fan speed).

Using a molex to 3-pin means you will be running the fan at full speed, direct from the power supply and thus do not require the sense wire. (It is possible to connect the sense wire to the motherboard while powering the fan direct, but we won't get into that just now).

The two wires should be black (ground) and red (+12 volts). The red wire should be the middle pin.


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## JamesBwoii (Dec 19, 2010)

gcavan said:


> I expect something else is wrong. The third pin is for RPM feedback sense (so the motherboard may read the fan speed).
> 
> Using a molex to 3-pin means you will be running the fan at full speed, direct from the power supply and thus do not require the sense wire. (It is possible to connect the sense wire to the motherboard while powering the fan direct, but we won't get into that just now).
> 
> The two wires should be black (ground) and red (+12 volts). The red wire should be the middle pin.


The adapter has 4 connectors on the end. Two of which are exactly as you stated, black and red, red in the middle. The other two are black and yellow, black in the middle. I might've been plugging it into the yellow one. I'll try the black and red one now. Thanks!



EDIT: I tried with the black aswell and still nothing.


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## GZ (Jan 31, 2010)

Check the 4 pin male molex connector. The contact pins have a tendency to get pushed out of place and not make contact.


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## JamesBwoii (Dec 19, 2010)

gavinzach said:


> Check the 4 pin male molex connector. The contact pins have a tendency to get pushed out of place and not make contact.


They appear to be fine.


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## GZ (Jan 31, 2010)

Then, there would appear to be something wrong with the molex adapter.

If you have a voltmeter or multimeter, you should test to be sure you are getting +12V at the fan connector.


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## JamesBwoii (Dec 19, 2010)

gavinzach said:


> Then, there would appear to be something wrong with the molex adapter.
> 
> If you have a voltmeter or multimeter, you should test to be sure you are getting +12V at the fan connector.


I contacted the person I bought them off and received a new one, which also doesn't work! Is it likely these are just low quality and that's why they're not working? They were around £1 ($1.64ish) for molex to 4 fan connectors.


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## GZ (Jan 31, 2010)

If you are getting power from the Molex plug, then you should be getting power from the fan connector. There is definitely a problem with the adapter if you are not getting power to the fan.


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## JamesBwoii (Dec 19, 2010)

This is getting ridiculous now, I've bought a new molex to 3pin adapter, this is my 3rd now, and it doesn't work. I know the molex is working because it powers my 120mm front fan. So why isn't it working?


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## GZ (Jan 31, 2010)

You have a multimeter, right? Test the leads to the fan connector... it should be putting out +12V.

If it is not, your adapter is faulty or not connected properly.


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