Normal—When this option is selected, PCIe resources are only allocated to devices installed at boot time, and PCIe hot-add is not supported.
Medium—When this option is selected, additional PCIe resources are allocated for each PCIe Root Port, which might enable a PCIe hot-add event to work without requiring a system reboot to enumerate the device.
High—When this option is selected, a maximum amount of PCIe resources are set aside to allow for the best chance of supporting a PCIe hot-add event.