4 pci express x16 slots (x8 link), 5 pci express x8 slots (x4 link), 6 pci express x1 slots (x1 link) – Asus P9D-C/4L User Manual
Page 38: 7 pci slots, 3 interrupt assignments

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Chapter 2: Hardware information
2.5.4
PCI Express x16 slots (x8 link)
The onboard PCI Express x16 slots provide one x8 link that supports VGA cards and various
server class high performance add-on cards.
2.5.5
PCI Express x8 slots (x4 link)
The onboard PCI-E slot 5 provide one x4 Gen3 link to CPU1. This slot supports various
server class high performance add-on cards.
2.5.6
PCI Express x1 slots (x1 link)
The onboard PCI Express x1 slots provide one x1 link.
2.5.7
PCI slots
The PCI slot supports cards such as a LAN card, USB card, and other cards that comply with
PCI 2.3 specifications.
* These IRQs are usually available for ISA or PCI devices.
IRQ
Priority Standard function
0
1
System Timer
1
2
Keyboard Controller
2
-
Programmable Interrupt
3*
11
Communications Port (COM2)
4*
12
Communications Port (COM1)
5*
13
--
6
14
Floppy Disk Controller
7*
15
--
8
3
System CMOS/Real Time Clock
9*
4
ACPI Mode when used
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
2.5.3
Interrupt assignments
Standard Interrupt assignments