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Successful first build! Need help with Molex case fans.

Last response: in Systems
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May 5, 2012 11:23:01 PM

Here are the basics of my build:

Case: Rosewill Ranger
Mobo: Asus P8Z68-V Pro/Gen 3
CPU: Intel i5-2500k LGA1155
PSU: OCZ ModXstream-Pro 600w
and a Coolermaster Hyper 212 Evo

(My GPU and HDD are still on the way.)


So I just spent the last two days building my first computer, and, much to my delight, it mostly works! The only thing I'm having trouble with are my case fans. This case comes already equipped with three fans. The one on the back, whose wire ends in in a small 3-pin that plugs straight into the motherboard, works fine. The two others (one on top, and and LED fan in front), have both a male and female Molex connectors.

My power supply has a cord that goes from the power supply to female molex head, continues on to a second molex head, and then ends at the small 4-pin thing that plugs into the motherboard.

Problem: I can NOT figure out how to wire this thing. I had assumed I would just plug the male head of each fan into the each of the female connectors on the power supply cord (leaving the two spare heads hanging), and then plug both into a single fan slot on my motherboard. I don't see any other way to do it, really.

But this does not work. The PC doesn't turn on at all with the fans plugged in. When I press the power button, all I get is a brief sound of electricity, and quick flash of the red CPU LED, and then... nothing. No fans, no beeps... Only the power button on the mobo shows any sign of life.

However, when I unplug the molex fans, everything works perfectly.
So I'm probably just a massive moron (this is my first build, after all), but can anyone tell me how I'm supposed to rig these Molex fans so that they function...and don't short out the entire PC?


Any advice would be appreciated!!
Thanks in advance. :) 



May 5, 2012 11:39:01 PM

KaraDactyl,

Don't plug the 4 pin into the motherboard.
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May 5, 2012 11:40:50 PM

Oh! ....Really?
What's it for?
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May 5, 2012 11:45:57 PM

That fixed the problem though! Haha, I knew I was doing something dumb.

Thank you so much! :D 
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May 6, 2012 4:10:53 AM

KaraDactyl,

The 4 pin connector at the end of the molex has current and the 4 pin connector on the motherboard also has current so when you connect them together you have a short.
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May 6, 2012 6:07:04 AM

The 4 pin at end is probably for floppy drive and not for MB.
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!