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Question If I connect my Molex case fan to the Mobo Fan header via adapter, can I control the speed?

Aug 1, 2021
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I have an older case that has a molex powered intake fan at the front. I want to be able to control it's speed like a PWM fan. If I buy a 4-pin to Molex Adapter and connect it to the motherboard's fan header, will it achieve that? And does a Molex connector also have that 3rd pin that transmits an RPM signal? Thanks.
 
I have an older case that has a molex powered intake fan at the front. I want to be able to control it's speed like a PWM fan. If I buy a 4-pin to Molex Adapter and connect it to the motherboard's fan header, will it achieve that? And does a Molex connector also have that 3rd pin that transmits an RPM signal? Thanks.
No, Molex connectors do not have speed sensing pin, only 2x Negative, +12 and +5v. 2 pin fans do not have speed sensors so can't be controlled from MB.
 
Aug 1, 2021
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No, Molex connectors do not have speed sensing pin, only 2x Negative, +12 and +5v. 2 pin fans do not have speed sensors so can't be controlled from MB.
I see. How about if I use a Fan header splitter like one of these:
https://www.newegg.com/p/1W7-0062-00004

And connect one end (the one without the 3rd pin) to the front fan via the 4-pin to Molex adapter, and connect the other end (with 4 pins) to a 3-pin exhaust fan I'm connecting to the back of the case. From what I understand, the motherboard only negotiates with the fan that has the 3 pins, and adjusts the current evenly among all connected fans. Will the motherboard then be able to adjust the speed of the Molex fan in front based on the input from the 3-pin exhaust fan at the back?
 
I see. How about if I use a Fan header splitter like one of these:
https://www.newegg.com/p/1W7-0062-00004

And connect one end (the one without the 3rd pin) to the front fan via the 4-pin to Molex adapter, and connect the other end (with 4 pins) to a 3-pin exhaust fan I'm connecting to the back of the case. From what I understand, the motherboard only negotiates with the fan that has the 3 pins, and adjusts the current evenly among all connected fans. Will the motherboard then be able to adjust the speed of the Molex fan in front based on the input from the 3-pin exhaust fan at the back?
Unlikely to work properly. What's so special about that one fan ? They are dime a dozen nowadays. Probably cheaper to replace than to adapt and still not get satisfactory results.
 
Aug 1, 2021
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Unlikely to work properly. What's so special about that one fan ? They are dime a dozen nowadays. Probably cheaper to replace than to adapt and still not get satisfactory results.
Thanks for the question. I never stopped to think that maybe that front fan was actually removable and not part of the chassis. After removing the front panel I realized that the fan can be removed if I temporarily unscrew the hard drive bays directly behind it. RGB fan here I come!
 

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