Assigning Irqs For Expansion Cards - Asus A7V266-EX User Manual

3. HARDWARE SETUP

3.7.2 Assigning IRQs for Expansion Cards

Some expansion cards need an IRQ to operate. Generally, an IRQ must be exclusively
assigned to one use. In a standard design, there are 16 IRQs available but most of
them are already in use, leaving 6 IRQs free for expansion cards. If your motherboard
has PCI audio onboard, an additional IRQ will be used. If your motherboard also
has MIDI enabled, another IRQ will be used, leaving 4 IRQs free.
IMPORTANT: If using PCI cards on shared slots, make sure that the drivers support
"Share IRQ" or that the cards do not need IRQ assignments. Conflicts arise between
the two PCI groups that will make the system unstable or cards inoperable.
The following table lists the default IRQ assignments for standard PC devices. Use
this table when configuring your system and for resolving IRQ conflicts.
Standard Interrupt Assignments
IRQ Priority
0 1
1 2
2 N/A
3* 11
4* 12
5* 13
6 14
7* 15
8 3
9* 4
10* 5
11* 6
12* 7
13 8
14* 9
15* 10
*These IRQs are usually available for ISA or PCI devices.
Interrupt Request Table for this Motherboard
PCI slot 1
PCI slot 2
PCI slot 3
PCI slot 4
PCI slot 5
AGPPro slot
ACR slot
Onboard audio controller
Onboard USB controller
Onboard IDE controller
ASUS A7V266-EX User's Manual
Standard Function
System Timer
Keyboard Controller
Programmable Interrupt
Communications Port (COM2)
Communications Port (COM1)
Sound Card (sometimes LPT2)
Floppy Disk Controller
Printer Port (LPT1)
System CMOS/Real Time Clock
ACPI Mode when used
IRQ Holder for PCI Steering
IRQ Holder for PCI Steering
PS/2 Compatible Mouse Port
Numeric Data Processor
Primary IDE Channel
Secondary IDE Channel
INT-A INT-B
— —
shared —
— shared
— —
— —
shared shared
shared —
— shared
— —
— —
INT-C INT-D
— shared
— —
— —
used —
— shared
— —
— —
— —
— shared
— shared
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