Dell PowerEdge C8000 - Manual (Page 273)

Troubleshooting 273
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.
PCI IRQ pool definition is the BIOS code assigned at run time.
IRQ Line Assignment IRQ Line
Assignment
IRQ0 8254 timer IRQ8 Real-time clock
IRQ1 Keyboard controller IRQ9 PCI IRQ pool definition
IRQ2 Cascade for IRQ9 IRQ10 PCI IRQ pool definition
IRQ3 Serial port (COM2) or PCI
IRQ pool definition
IRQ11 PCI IRQ pool definition
IRQ4 Serial port (COM1) or PCI
IRQ pool definition
IRQ12 Mouse controller
IRQ5 PCI IRQ pool definition IRQ13 Processor
IRQ6 PCI IRQ pool definition IRQ14 Primary IDE controller
IRQ7 Reserve IRQ15 Secondary IDE controller