The goal of a subsystem is to actively reduce the power consumed beyond that of reducing passive power consumption (i.e. the energy consumed by the devices alone). Using lower power devices is good, but the subsystem approach takes that to even a higher level of savings. Subsystems can also be created with digital signals to assist processors in evaluating the current state. For example, cable disconnect detection on a cable driver can feed information back to a digital core to disable other sections of the system when that output is no longer in use. This can be highly useful on switches or other devices with many outputs – in many cases, not all the outputs are in use. Additionally, many subsystems can work autonomous from a CPU or digital core and still provide feedback on the current state, acting in near real time off-loading the processor or FPGA while maintaining very high response times.