Connecting MOLEX fans to the motherboard

[Joeyob32]

Hi guys,
This may sound like a stupid question, but I've been manually opening/closing my case anytime I needed to change the speed of my fans (Antec 900 - 4Xswitched MOLEX fans) and was considering taking advantage of the 4 fan headers on the motherboard. The thing is, the motherboard contains 2 X 3 pin headers, and 2 X 4 pin headers. I managed to find the converters for the 3 pin headers, no problem but cant seem to find a converter for 4-pin fan -> Molex anywhere!

That said, I have 2 questions for any brave soul whos kind enough to help:

1) Is there such a thing as a 4-pin fan -> molex adaptor?

2) Am I likely to damage the motherboard putting all this voltage through it that's normally just coming straight from the PSU? (Also overclocking)

Thanks in advance guys!

 

[blazorthon]

You can plug a 3 wire fan plug into a four pin header. I don't think there are any Molex to 4 pin headers because the fourth wire is used for varying the fan speed in a way that a Molex fan does not support.

The motherboard shouldn't be damaged by using fan headers that are on it. I see no reason for that to cause damage. Besides, fans don't use that much power.

 

[geofelt]

1) yes.
2) A motherboard fan header usually has a limited amperage capability. One fan is probably OK. Two or more may not be.

It is a moot point, I think.
A molex fan can only change speed via a voltage reduction.
Such a connection will not have the speed sensing lead which makes automated speed adjustments practical.

My suggestion is to buy a front panel mounted fan speed controller.
Here is an example.
http://www.newegg.com/Product/Product.aspx?Item=N82E16811992012&cm_re=fan_controller_5.25-_-11-992-012-_-Product

 

[Joeyob32]

Thanks guys, so just to clarify, if I use the MOBO header, I wont be able to change the speed of the fans anyway, so I'll still have to open/close the case to change the speed?

Also, I know this might sound dumb, but would a fan controller be able to change the speed on a MOLEX only fan?

Thanks again!

 

[geofelt]

How are you now changing speeds of your molex fans now?

Some newer motherboards have some smart capabilities to deal with mobo attached fans.
They can accept either 3 pin fans which are controlled by voltage, or 4 pin fans that are controlled by PWM(Pulse Width Modulation) Speed is controlled by quickly turning the fan on or off.
Either type makes use of the third wire to sense fan speed. The main two wires are + and - voltage leads.

A front panel controller accepts molex or other fan inputs and outputs a reduced voltage to the fans so they spin slower.
A Rheostat is the typical mechanism.

 

[Joeyob32]

The fans that I have come with inline switches with 3 different settings (L M H) which I tinker with way more often than Id like. Its a major chore. I just went and bought a Sentry 3 fan controller anyway, and 4X Molex -> 3 pin fan adaptors, hope that this works. Even if I did connect the fans to the motherboard header, that'd only count for 2 of the 4 without daisychaining, which Im worried might be a dodgy move. Thanks for all the help though!

 

[geofelt]

The fans that I have come with inline switches with 3 different settings (L M H) which I tinker with way more often than Id like. Its a major chore. I just went and bought a Sentry 3 fan controller anyway, and 4X Molex -> 3 pin fan adaptors, hope that this works. Even if I did connect the fans to the motherboard header, that'd only count for 2 of the 4 without daisychaining, which Im worried might be a dodgy move. Thanks for all the help though!

Looking at the controller I linked, it connects to either 3 or 4 pin fan leads.
If your case fans have either, you are ok.
If your fans have molex connectors (white/black with 4 rounded holes) only then you want a different controller or you will need some molex to 3 or 4 pin adapters.
Some fans will have both molex and 3 pin connections so you can do either.

 

[Joeyob32]

The fans that I have come with inline switches with 3 different settings (L M H) which I tinker with way more often than Id like. Its a major chore. I just went and bought a Sentry 3 fan controller anyway, and 4X Molex -> 3 pin fan adaptors, hope that this works. Even if I did connect the fans to the motherboard header, that'd only count for 2 of the 4 without daisychaining, which Im worried might be a dodgy move. Thanks for all the help though!

Looking at the controller I linked, it connects to either 3 or 4 pin fan leads.
If your case fans have either, you are ok.
If your fans have molex connectors (white/black with 4 rounded holes) only then you want a different controller or you will need some molex to 3 or 4 pin adapters.
Some fans will have both molex and 3 pin connections so you can do either.

Yeah, they only have the molex connectors, the switches and nothing else. There are no words to how much Im looking forward to not having to open my case for a while!

 

[geofelt]

The molex connectors mentioned in the controller description will be going to the psu, not to your fans as you may think.
Look carefully at your fan connectors and compare them to the connectors on the controller that go to the individual controls.
I think they are 3 or 4 pin connections.
That means that you will need some molex to fan adapters like this:
http://www.amazon.com/Rosewill-12-Inch-Power-Supply-RCW-311/dp/B003MAD8RC/ref=sr_1_27?s=pc&ie=UTF8&qid=1447276679&sr=1-27&keywords=molex+to+fan+adapter