[SOLVED] Molex fan control by splicing the voltage inputs?

[JottoJotto]

In theory, would it be possible to rewire a molex fan to have voltage control by splicing a three pin fan connection to the 12 V wire? Then moding the molex connector to the fan for 5v. It will always run at 5 volts, but then be able to use the 3 pin connector to voltage regulate based on temps.

 

[lvt]

In theory, would it be possible to rewire a molex fan to have voltage control by splicing a three pin fan connection to the 12 V wire? Then moding the molex connector to the fan for 5v. It will always run at 5 volts, but then be able to use the 3 pin connector to voltage regulate based on temps.

You can get 5V, 7V and 12V from a Molex connector, but it has nothing to do with the temperature.

Temperature based fan control uses different principle.

 

[Lutfij]

Welcome to the forums, newcomer!

You're essentially asking how to make a fan run off of a USB's power source, yes it's possible. I've done it in the past...just that it isn't a sight to behold. You might want to ditch the Molex fan idea and pick up a fan that's got 3pin DC or 4pin PWM. That should serve you well over the long run. There are tonnes of guides on the www but you can take a look at this one.

You could tether the fan header to operate off of a heat source, meaning that the voltage is regulated by the board but you will need the third wire

 

[JottoJotto]

Welcome to the forums, newcomer!

You're essentially asking how to make a fan run off of a USB's power source, yes it's possible. I've done it in the past...just that it isn't a sight to behold. You might want to ditch the Molex fan idea and pick up a fan that's got 3pin DC or 4pin PWM. That should serve you well over the long run. There are tonnes of guides on the www but you can take a look at this one.

You could tether the fan header to operate off of a heat source, meaning that the voltage is regulated by the board but you will need the third wire

Thanks for the welcome!

Naw, I was trying to rewire It to a usb. I was trying to rewire it to work on a 3 pin connection, but apparently I don't understand how 3 pins fans work. Also, I can enlist the help of a friend who has wiring experience to make pretty wires.

Basically, I'm using a 2 slot blower fan as an exhaust in the vertical mount pci slots to pull the air out of the case that's coming out of the GPU radiator and it's difficult to find one that has a three/four pin connection.

You say I'd need a third wire to run it on three pin but I'm assuming if the fan is molex, it doesn't have a the ability to send the tachometric signal on pin three. But if this signal is not present, will the fan stop functioning all together?

Also, the molex fan pinout shows two voltages on two wires, a 12 v and a 5 volt. I know you can mod molex fans to run on 5 volts, but is there a way to wire it the pin it uses on the molex switches depending on the voltage. Or is this overly complex?

I may just install for the molex fan and run it directly off the power supply.