thank you so much for taking some time out of your day to answer my question.

I have bought this Laptop HeatSink/Fan combination and it comes with a molex connector at the end of the wire to attach to a male molex connector. enter image description here

As you can see on the bottom left corner, the Molex connector is present; however my project involves hooking the fan up to a USB to power the device. What went wrong the first time I did this is that when stripping and soldering the wires, they were so fragile and small that they broke easily.

So, I was wondering is there a way that I can connect this molex connector to a male molex (more secure than soldering thin wires) and somehow get power to the fan still?

I can't seem to find a molex connector and wire the same size as the one in the picture, and neither can I find some way to connect the wire to a place in which I can power the fan from a USB cable.

As a side note I only need power, no speed or power adjustments as I want the item to run at maximum speed always. Thank you.

  • \$\begingroup\$ Unless you have the right male connector it will be quite difficult to make contact to the wires. And even if you have that connector, it has a small pitch (distance between the connection) so that is difficult as well for the inexperienced. Personally I'd just cut off the connector, then strip the black and red wires and solder those to a USB lead. I'd make it secure with some heat-shrinking tube. But, yeah, I have a experience with that and I have the tools right here. \$\endgroup\$ Commented Aug 30, 2017 at 19:20
  • \$\begingroup\$ standard 0.1" 2 pin header and 12V to red, 0V to blue, Yellow is for tach. with blk as return to 0V \$\endgroup\$ Commented Aug 30, 2017 at 19:22

2 Answers 2


I will try to help but as I am not aware of the specifics of your fan, I can only give you hints based on my past experiences with fans.

Usually they have 4 connections (just like yours):

  1. V+
  2. GND
  3. tachometer
  4. PWM control

Then it is a matter of guessing which one does what...

The only problem I forsee is that V+ is usually +12V (at least in desktop computer it is) thus you might have trouble getting the fan to full speed with 5V if this is the case for your fan.

Usually you will have the blue be the PWM, and it should stay disconnected to get full rpm source

What I would recommend is to cut the connector altogether, strip the wire and experiment a little with a lab power supply (or a 9V battery) to determine which of the yellow or the red is V+. Computer fans should be very well protected, and if you keep the black wire as GND you will most probably be fine.

Then if you manage to get it to run fast enough for your need on 5V it is just a matter of finding an old USB cable, strip it, and solder the 5V on V+ of the fan (either red or yellow, most probablly red) and GNDs together.

If you need it to run faster, you shoul buy a step-up converter (cheap modules available everywhere), and solder it between your USB cable and your fan. This will draw quite a bit more current from your USB (no power is free in this day and age) so make sure you use a modern USB port that will handle the current without going into short circuit safety.


A picture of what you're trying to connect it to would be nice, is it an actually port? of which usb type?

There exists 4 pin molex to usb adapters that you should be able to just plug in at both ends if its a port.


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