How to control fan speed when they are plugged into USB?

[Sanderguy777]

I built a tray for my laptop and have two 120mm fans on it that are supposed to help air go into the little 40mm intakes that Asus put on the bottom (where ones knees would go lol) of the laptop. 

 

Anyway, I'm waiting on the part that adapts the fan header connection to USB so I can actually power the fans. The one I got has a splitter built in, so it can power two fans, has a switch to turn them on and off, and then the USB plug. 

 

What I'm wondering, is whether there is a simple way to control the fan speed through software, or some bit of plug and play hardware (hopefully a knob or something). 

 

Any ideas? I'm no electrical engineer or elecchicken, so any manufacture of parts needs to be simple and non mathy LOL. 

[Neggy-Z]

There wouldn't be a way to control them via software.

You could get a usb potentiometer, will give you voltage control for the fans.

Not sure how these go long term, if they can put more stress on the usb port/risk of burning out the port, but i have one connected to my routers usb port to power a couple of 120mm fans to cool down my networking/internet gear and it seems to be doing a good job.

One thing to keep in mind would be how many amps your usb port can provide.

[Sanderguy777]

46 minutes ago, Neggy-Z said:

There wouldn't be a way to control them via software.

You could get a usb potentiometer, will give you voltage control for the fans.

Not sure how these go long term, if they can put more stress on the usb port/risk of burning out the port, but i have one connected to my routers usb port to power a couple of 120mm fans to cool down my networking/internet gear and it seems to be doing a good job.

One thing to keep in mind would be how many amps your usb port can provide.

I think that might work. How many amps does that use? I could plug it into the usbc (which CHARGES at 100w, but I font know how much it can go in the other direction...)

[Neggy-Z]

The potentiometer itself shouldn't be pulling a meaningful amount of amps, besides the small losses from altering the voltage (if that's how it even works) your still limited by how many amps the fans themselves pull.

You shouldn't have any issues with standard 120mm fans.