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80 Troubleshooting Your System
Troubleshooting IRQ Assignment Conflicts
Most PCI devices can share an IRQ with another device, but they cannot use an IRQ simultaneously. To
avoid this type of conflict, see the documentation for each PCI device for specific IRQ requirements.
Table 4-2 lists the IRQ assignments.
Troubleshooting External Connections
Loose or improperly connected cables are the most likely source of problems for the system, monitor, and
other peripherals (such as a printer, keyboard, mouse, or other external device). Ensure that all external
cables are securely attached to the external connectors on your system. See Figure 1-2 for the back-panel
connectors on your system.
Table 4-2. IRQ Assignment Defaults
IRQ Line Assignment
IRQ0 System timer
IRQ1 Keyboard controller
IRQ2 Interrupt controller 1 to enable IRQ8 through IRQ15
IRQ3 Serial port 2 (COM2 and COM4)
IRQ4 Serial port 1 (COM1 and COM3)
IRQ5 Remote access controller
IRQ6 Diskette drive (optional) controller
IRQ8 Real-time clock
IRQ9 ACPI functions (used for power management)
IRQ10 Available
IRQ11 Available
IRQ13 Math coprocessor
IRQ14 IDE CD drive controller
IRQ15 Available
book.book Page 80 Tuesday, August 25, 2009 1:14 PM