Addressable RGB (also known as ARGB or Digital RGB, DRGB) is a standard RGB interface used by a wide variety of PC components, light strips, motherboards, and controllers. It consists of a 3-pin connector which provides power and data and is capable of controlling each LED on the device with its own unique color value.

Addressable RGB LEDs work in a "daisy chain" configuration where the data signal goes from the controller into the first LED, then to the second LED, then to the third, and so on. As this interface is only capable of sending data in one direction, OpenRGB is unable to automatically determine how many LEDs are in the chain for any given device or chain of devices. Therefore, it is required that you manually configure the number of LEDs for each ARGB output in OpenRGB before you can control the attached LEDs. This process is called "resizing".

There are two methods for configuring the number of LEDs on an addressable header in OpenRGB. The first method is presented upon opening OpenRGB for the first time with an addressable RGB controller or motherboard present. The interface looks like this:

The second method can be accessed at any time. It involves selecting the Zone that corresponds to a given ARGB output in the Zones selection box and then clicking the Edit Zone button. This opens a new menu that allows you to enter the zone size (LED count) as well as perform additional customization such as defining segments. Segments can be used to divide up a zone into smaller sections for more flexibility.

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 strings 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.