Fans, motherboard control, and molex power

[bamato]

I'm trying to decide on a fan controller for an upcoming build and am not even sure if what im trying to accomplish is possible. Essentially, I want to power fans on my psu's 12v rail or molex, but still allow the mobos 3 pin fan header to control the fans speed (mobo has 3 pin fan control).

Or, is there a controller that can hook up via usb and use the mobos sensors to control fan speed rather than have probe wiring everywhere?

The reason for all of this is I dont have the luxury of a drive bay to mount a controller.

 

[ehume]

The answer to your need is PWM. Pulse Width Modulation. Look it up, do your homework. With a PWM splitter you can control multiple fans from the motherboard and get their power from Molex. No other fan controller needed.

But look up PWM and do your homework. After you learn a bunch of stuff you will know what to do.

 

[bamato]

Perhaps I wasn't clear enough. I want to control 3 pin fans. Not 4 pin PWM. I'm well aware of what PWM can do. And running up to (10) fans on one PWM header would blow that fan header.

 

[NiHaoMike]

You'll need a buck converter controlled by the motherboard signal. It's pretty easy to design one for someone experienced with electronics, but I'm not aware of any off the shelf solution.