A filler panel is an metal or plastic enclosure that does not contain any functioning system hardware or cable connectors. Filler panels occupy vacant component slots to help control noise, EMI, and airflow. They are installed at the factory and must remain in the server until you replace them with a component. If you remove a filler panel and continue to operate your system with an empty slot, the server might overheat due to improper airflow. Additionally, some components are installed but are not powered (DPCCs, fan modules). As with filler panels, these components must remain installed in a fully powered-on server.