Molex fan to 3 pin adapter question!

xStampede · May 17, 2014

Hi, i have few fans from older PC case that can be connected only throu molex, the problem is they are high airflow high noise so if connected throu molex they work only at max speed. I found an 3pin to molex adapter(or molex to 3 pin, not sure(looks like this one http://www.acousticpc.com/cables_acoustic_pc_4_pin_molex_to_3_pin_power_adaptor_12_volt.html).

So can i safely connect the molex fan to the molex to 3 pin adaptor and then to motherboard and control the fan speed using SpeedFan software, or is there a change i burn the fan or the mobo or something?

xStampede · May 17, 2014

Realized that adapter wouldn't do, it's female.

I need an adapter like this right, can you guys confirm that if i buy this i will be able to control speed on my molex case fan's? http://www.rodocomp.si/revoltec-adapter-pin-pin-molex-rc020-p-2627.php

photonboy · May 17, 2014

http://www.intel.com/support/motherboards/desktop/sb/cs-012074.htm

The FAN_TACH signal from the fan back to the motherboard isn't present so the computer would have no idea how fast the fan is spinning thus can't control its speed.

It also wouldn't work if the fan wasn't a variable fan which it probably isn't since it doesn't have the correct connector to be controlled.

xStampede · May 17, 2014

photonboy :

What about controlling the fan via voltage, by lowering voltage the fan would spin slower, making it go slower shouldn't harm it i think.

animal · May 17, 2014

you would probably need something more like this:

http://www.frozencpu.com/products/1115/cab-37/3_Pin_Female_Standard_Power_Connector_to_4_Pin_Male_Standard_Power_Connector.html?tl=g47c251s634

However, depending upon your needs (i.e.-what ends do you require....male or female?) you can check out all the cables they carry here:

http://www.frozencpu.com/cat/l3/g47/c251/s634/list/p1/Fan_Accessories-Fan_Cables-3_Pin_Adapters-Page1.html

geofelt · May 17, 2014

A molex fan connector will nave no speed sensing wire for the motherboard to sense.
You can make your own reduced speed adapter, or buy something like this:
http://www.newegg.com/Product/Product.aspx?gclid=CLqJlMevs74CFTBk7AodqAkAQQ&Item=N82E16812311003&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-Internal+Power+Cables-_-N82E16812311003&ef_id=U3eNXwAAAXUoxmYa:20140517162503:s

Or this: http://www.moddiy.com/products/Molex-4%252dPin-Fan-30%25-Power-Lead-Reduction-Cable.html

xStampede · May 17, 2014

animal :

Do you know if i will be able to control the voltage with that adapter?

nukemaster · May 17, 2014

You can control the voltage with an adapter(as long as your board can control voltage and handle the current draw of the fan.)

The linked adapter would have the "3" pin header on the board and connect to a 4 pin(molex) fan(do not stack too many fans with this solution as it loads the board).

Most boards are good for about 1 amp on voltage controlled fans.

Your fan will control even if the board can not see the speed. You just will not be able to tell how fast it is going(well you can look at it

). I have controlled those slot blowers without speed sense without issues.

With PWM getting as common as it is, You should consider starting to get PWM fans for the future since they can be voltage or PWM controlled and newer PWM only boards will not control 3 pin(or 2 pin) fans.

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Molex fan to 3 pin adapter question!

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