Rgb fans are exactly what they are as described. An RGB lightstrip glued to a fan. Seperate things, one is generally 5v, the other is 12v. That means seperate wiring, seperate headers, seperate controls.
That means unless properly wired and properly setup with whatever software is needed, you can have a complete light show and the fans not spin, or a fully functional fan with no lightshow.
So you'll need to check all the wires are connected correctly, and the necessary software is activated and set for the fans.