Asus P4T P4T User Manual - Page 28

3. H/W SETUP Expansion Cards 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. Standard Interrupt Assignments IRQ Priority Standard Function 0 1 System Timer 1 2 Keyboard Controller 2 N/A Programmable Interrupt 3* 11 Communications Port (COM2) 4* 12 Communications Port (COM1) 5* 13 Sound Card (sometimes LPT2) 6 14 Floppy Disk Controller 7* 15 Printer Port (LPT1) 8 3 System CMOS/Real Time Clock 9* 4 ACPI Mode when enabled 10* 5 IRQ Holder for PCI Steering 11* 6 IRQ Holder for PCI Steering 12* 7 PS/2 Compatible Mouse Port 13 8 Numeric Data Processor 14* 9 Primary IDE Channel 15* 10 Secondary IDE Channel *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 AGP slot Onboard USB controller SMBus INT-A - shared - - - shared - - INT-B - - shared - - - - shared INT-C shared - - shared - - - - INT-D - - - - shared - shared - 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 will arise between the two PCI groups that will make the system unstable or cards inoperable. 28 ASUS P4T User's Manual