IRQ Conflicts
Use this procedure if Windows XP will not start or install, or crashes/hangs at regular intervals.
Tracing IRQ Conflicts
Pull out all unnecessary cards, that is, all cards you do not need to make the machine just work. That means CD drives, additional hard disk controllers, sound cards, video and TV cards, PCI/USB cards, everything and anything that will not prevent the machine booting. If your modem is internal, take it out, too. If it's external and is plugged into an onboard serial port, you can probably leave it.
Many modern BIOS will tell you what IRQ what PCI slot is allocated to onboard devices, such as USB and sound devices. Check the BIOS IRQ assignments and do not put cards in slots that are shared with on-board devices.
If you cannot find out the motherboard IRQ assignments from your BIOS, consult your manufacturer's website or the manual that came with your system.
If you still cannot determine what IRQs are shared, plug one card in and keep moving the card from slot to slot and restarting your machine until the device conflict is resolved or you run out of slots, whichever comes first. Repeat for each card.
Manually Assigning IRQs in Windows XP
If you are unable to resolve your IRQ conflict, you may need to assign IRQs manually. ACPI (Advanced Configuration and Power Interface) is an open industry specification developed by Hewlett-Packard, Intel, Microsoft, Phoenix, and Toshiba. ACPI establishes industry-standard interfaces for OS-directed configuration and power management on laptops, desktops, and servers. If your system is ACPI compliant, then ACPI will assign the IRQs. In order to manually assign IRQs, the Hardware Abstraction Layer (HAL) must be changed to Standard PC with APM support.
In Device Manager, expand "Computer" and right click the expanded entry. Select Update Driver, then choose "Install from a list or Specific Location (Advanced)", click Next. Select "Don't Search, I will choose the driver to install.", click Next. If Standard PC is shown in the list, choose it, otherwise untick Show compatible hardware, then select Standard PC from the list. Click Next.
Other Resources
A General Description of IRQ Sharing in
Windows XP
This article offers a general description of how interrupt request (IRQ) sharing is managed in Windows XP. The description includes an explanation of why many of the devices on your computer seem to use the same IRQ and why Windows XP does not include resource rebalancing.
How to Manage Devices in Windows XP
Device Manager provides a graphical view of the hardware that is installed on the computer, as well as the device drivers and resources associated with that hardware. Using Device Manager provides a central point to change the way the hardware is configured and interacts with the computer's microprocessor.
How to Configure Devices By Using Device Manager
This step-by-step article describes how you can configure devices by using Device Manager in Windows XP. When you install a Plug and Play device, Windows automatically configures the device so it will work properly with the other devices that are installed on your computer. As part of that configuration process, Windows assigns a unique set of system resources to the device you are installing.
Revision Date: 29 Nov 2003