No, that is NOT the same as a USB header.
The system that comes with Corsair's 3-pack of LL120 RGB fans consists of two boxes. One is the hub for the ARGB cables from each of the fans. The other is their Lighting Node Pro, the controller box that sends power and control signals to that Hub. The Lighting Node Pro requires four things to work:
- A power supply, using a supplied cable from a Node port to a PSU SATA power output;
- A supplied cable connecting the Node to that Hub;
- A supplied cable from a Node port to a mobo USB2 header for communication; and,
- The Corsair iCue software utility, downloaded free from their website and loaded in your computer.
iCue does all the controlling (provides you with a software interface to do this) and communicates all its info to the Lighting Node Pro via that USB2 connection. So the USB2 header is NEEDED for this to work.
Tell us what mobo maker and exact model number you have so we can look up its specs. Then tell us what you have already plugged into mobo USB headers, since you say they all are in use already.