Most addressable LED strip types only require a data signal for control. The frequency of the control signal is fixed for these types. However, there are also addressable LED types that require a clock signal in addition to the data signal. With these types, a clock signal is transmitted from the controller to the LED strips. In this case two GPIOs are needed for the control and these must be set correctly in the WLED settings. The advantage is that the clock control enables faster data transfer from the controller to the LED strips. Faster effects can be run with a large number of LEDs.