116 Troubleshooting Your SystemChecking the EquipmentThis section provides troubleshooting procedures for external devices attached to the system, such as themonitor, keyboard, or mouse. Before you perform any of the procedures, see "Troubleshooting ExternalConnections" on page 116.Troubleshooting IRQ Assignment ConflictsMost PCI devices can share an IRQ with another device, but they cannot use an IRQ simultaneously. Toavoid this type of conflict, see the documentation for each PCI device for specific IRQ requirements.Table 4-2 lists the IRQ assignments.Troubleshooting External ConnectionsLoose or improperly connected cables are the most likely source of problems for the system, monitor, andother peripherals (such as a printer, keyboard, mouse, or other external device). Ensure that all externalcables are securely attached to the external connectors on your system. See Figure 1-2 for the front-panelconnectors and Figure 1-4 for the back-panel connectors on your system.Table 4-2. IRQ Assignment DefaultsIRQ Line AssignmentIRQ0 System timerIRQ1 Keyboard controllerIRQ2 Interrupt controller 1 to enable IRQ8 through IRQ15IRQ3 Serial port 2 (COM2 and COM4)IRQ4 Serial port 1 (COM1 and COM3)IRQ5 Remote access controllerIRQ6 Diskette drive controllerIRQ7 ReservedIRQ8 Real-time clockIRQ9 ACPI functions (used for power management)IRQ10 AvailableIRQ11 AvailableIRQ12 PS/2 mouse port unless the mouse is disabled through the System Setup programIRQ13 Math coprocessorIRQ14 IDE CD drive controllerIRQ15 Available
