Asus P4B - Pci Irq Resource Exclusion

ASUS P4B motherboard user guide 4-23
IRQ XX Reserved [No/ICU]
These fields indicate whether or not the displayed IRQ for each field is
being used by a legacy (non-PnP) ISA card. The setting [No/ICU] for an
IRQ field indicates that you are using the ISA Configuration Utility (ICU),
and that this particular IRQ is NOT required by a legacy ISA card. Set the
IRQ field to [Yes] if you install a legacy ISA card that requires a unique IRQ
and you are NOT using ICU. Configuration options: [No/ICU] [Yes]
4.4.3.1 PCI IRQ Resource Exclusion