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Questions about fans I have

Last response: in Components
December 5, 2010 4:03:10 PM

Hello, I've got two Delta 120x25mm 150.33 CFM fans and I've got an issue. I wish to connect them to my Lamptron FC5V2 fan controller but the problem is this... there's a male molex 4-pin connector on each fan which I'm guessing is used for power and 1 3-pin RPM connector for each fan. My questions are this...

1) Can I connect the 3-pin RPM line to the fan controller to control its speed, and the male 4-pin molex connectors to the power supply to control it?


2) Find a female-to-female 4-pin molex cable and a 4-pin to 3-pin cable to connect it to the fan controller (disregarding the RPM wire altogether)?

Or is there another way?

Thanks in advance! :) 

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Best solution

December 5, 2010 4:25:30 PM

If your fan controller has its own power supply all you need to do is attach the 3 pin to the fan controller.

If your fan controller doesn't you'll need to power the fans via the 4 pin molex.

Even though the 4 pin will provide continuous power it will still be adjusted via the controller.

I think thats what your asking anyway. :heink: 

December 5, 2010 4:29:00 PM

Yes, it has its own power supply of 30W per channel but if I power the fans from the power supply instead of the fan controller, can I still control the fan's speeds from the fan controller via the RPM line? Or must I buy an additional 2 cables to convert the 4-pin males to female and then to 3-pin so it can be connected and powered by the fan controller?
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December 5, 2010 4:42:50 PM

The power needs to pass through the controller for it to work, I think if you just connected the rpm line to the controller and the 4 pin molex directly to the fan from the psu it would just spin full speed.

I would say is try it, you will soon find out and won't risk damaging anything.

Are you on about these?

December 5, 2010 4:52:33 PM

The fan's molex connections are only two wires (for power) while the RPM line is just a single wire 3-pin connection which is separate altogether. I guess I can just ignore the RPM line in this case.

I've actually got a few of those cables however to connect the 4-pin from the fans to that wire I have to get a couple female-to-female molex wires like here to be able to correctly connect the fans to the conversion cable pictured above (because the fans have male molex connectors, not female hence the conversion needed). I thought I could get away with just powering the fans from the power supply via the 2 wire 4-pin molex line and controlling speeds from the 1 wire 3-pin RPM line but it doesn't look like I can.

Thanks! :) 
December 5, 2010 5:20:38 PM

Shame there's no way to convert both the two wire 4-pin molex power and the one wire 3-pin RPM line back into one cable. :p  Not even sure that'd function correctly. It's fine, I can use the fan controller to power the fans and disregard the RPM line.
December 5, 2010 5:35:40 PM

Thanks a lot. :) 
December 15, 2010 12:26:51 AM

Best answer selected by carnageking.