A power sourcing unit for a power over ethernet system. The unit includes a chassis with a power supply guide and a CPU guide, and a power supply including a power supply connector. The unit also includes a printed circuit board including first and second connectors and being coupled to a plurality of RJ-45 jacks, and a CPU line card including a CPU connector. The power supply guide engages the power supply to allow the power supply to be slid into and out of the unit to couple the power supply connector to the first connector of the printed circuit board. The CPU guide engages the CPU line card to allow the CPU line card to be slid into and out of the unit to couple the CPU connector to the second connector of the printed circuit board. The CPU line card allows the unit to be coupled to a network. Multiple power sourcing units can be daisy-chained together.