The server might be shipped with module-replacement filler panels for storage drives and PCIe cards. These filler panels are installed at the factory and must remain in the server until you replace them with a purchased option.
Before you can install an optional server component into the server, remove the filler panel from the location into which you intend to install the component. When you remove a storage drive or a PCIe card from the server, install either a replacement for the component removed or a filler panel.