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Controlling fan speed through 4-pin molex?

Last response: in Overclocking
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December 4, 2010 11:39:03 AM

Hey there folks!

So here's the situation. I recently built my first computer using the Thermaltake Armor A90 chassis. It has great cooling; 120mm intake at front, 200mm and 120mm exhaust at top and back. I'm not overclocking, and speedfan shows a System temp of 36C and CPU 43C at idle, which is great am I right? (I'm pretty new to this)

Unfortunately, the 200mm and the front intake fans both only have 4-pin molex connectors, so I can't hook them up to the motherboard to control fan speed (the 120mm exhaust hooks up and is controlled to 600RPM. The mobo has space for another 2 case fan connections). I'm trying to make my computer silent, and seeing as the temps are all a-ok, I figured I could try and slow down the fans a bit. So what are my options with these molex connector fans? I'd idealy like to connect them straight up to the mobo, so that the speed-control occurs automatically.

I've done a bit of browsing, have come up with 3 options:

1. PCI slot speed controller
http://www.techbuy.com.au/p/127376/COOLING_CONTROLLERS/...
Although my impression of these is that they if you have a PWM fan, 3 pin connector but don't have the adequate spot on the mobo to plug the connector into.

2. Something like the zalman fan controller
http://www.techbuy.com.au/p/44329/COOLING_CONTROLLERS/Z...
Although again, needs a 3-pin connector?

3. A more hefty multi-fan controller with inbuilt sensors, eg NZXT controller
http://www.techbuy.com.au/p/135271/COOLING_CONTROLLERS/...
Has connections to accomodate 4-pin molex.

My question - am I correct in saying that options 1 and 2 would not work for my situation, and that 3 should work? The NZXT site says it works by varying the voltages to the fan; does this work in altering fan speed through the 4-pin molex? I thought you need PWM to alter fan speed?

Okay this is a pretty long winded post and more than one question, but thank in advance for all your help! :D 

Best solution

a b K Overclocking
December 4, 2010 12:26:28 PM

Its a simple solution if there are 3 wires coming from the case fans... buy any 3 pin mobo connector cable for the fan, mod by cutting and connecting the respective wires and connect to mobo...

But if the fans have only 2 wires then you can do it only by fan controllers... you can still mod the fan cable like above but with two connections (live and ground) and then connect them to any fan controller...

Its better to connect one fan to one controller so that rules out the first and second ones... With the NZXT Sentry 2 you dont even need to mod the cables... and it looks cool too...
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December 5, 2010 12:15:03 AM

I just checked - 2 wires. I reckon I'll go with the NZXT!

Thanks for your help! :) 
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December 5, 2010 12:15:29 AM

Best answer selected by outsidemyself.
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