NetApp Hardware Universe is the authoritative resource for platform-specific hardware compatibility, supported adapter configurations, and slot priorities. When adding an FC adapter or another I/O module to an ONTAP controller, the administrator must verify that the adapter is supported by the specific controller model and determine the correct or preferred PCIe slot. NetApp installation documentation explicitly directs administrators to Hardware Universe when multiple slots are available so that the documented slot priorities are followed. The Interoperability Matrix Tool validates interoperability among ONTAP releases, hosts, HBAs, drivers, firmware, switches, and related components, but it is not the primary source for controller slot placement. Relevant SAN ONTAP topics include Hardware Universe, controller I/O architecture, FC adapters, PCIe slot priorities, hardware compatibility, and installation planning.