OpenRGB will need to know the number of lighiting elements connected to each header to properly display and control each one. It is also useful to size the elements even if useing the built in modes so a rainbow wave or bounch effect ends at the end of the lighting element.

Most common RGB hubs, splitters or cables will just dupilcate the signal (putting all elements in parallel). When setting up the size of the elements, it will be ideal for all stings to be the same length so ARGB effects will wrap at the same time.

Some elements like fans and LED strips can be chained to together to create one long strip. To calcuate the length, add up the number of LEDs in each individual element. If using all elements of the same type, mutiply the number of LEDs per element by the number of elements in the chain.