138 Troubleshooting Your System
Checking the Equipment
This section provides troubleshooting procedures for external devices
attached to the system, such as the monitor, keyboard, or mouse. Before you
perform any of the procedures, see "Troubleshooting External Connections"
on page139.

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. Table4-2 lists the IRQ
assignments.
The USB CD drive activity indicator. See "Troubleshooting a USB Device" on
page143.
The CD drive activity indicator. See "Troubleshooting an SD Card or Internal
USB Key" on page152.
The hard-drive activity indicator. See "Troubleshooting a Hard Drive" on
page155.
An unfamiliar constant scraping or
grinding sound when you access a
drive.
See "Getting Help" on page175.
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 Reserved
Table 4-1. Start-Up Routine Indications (continued)
Look/listen for: Action