IRQ Conflicts between PCI Boards and Non-PCI Boards in Windows

Updated Jan 3, 2018

Issue Details

I have a PCI board and a non-PCI board installed on my computer, but Device Manager shows a resource conflict between the two boards. How can I resolve the conflict?


  1. Remove the conflicting PCI board.
  2. Restart the computer.
  3. Enter the BIOS setup.
    1. If there is an Advanced menu (locations differ from BIOS to BIOS), there most likely will be a setting to reserve IRQs.
    2. You should mark the IRQ that was shared as Reserved and restart the computer.
    3. If you are not able to find the option in your BIOS to reserve IRQs, you may need to contact your PC manufacturer to obtain a version of the BIOS that permits the ability to reserve IRQs.
  4. Shut down the computer.
  5. Reinstall the PCI board.
    1. You may have to reconfigure the non-PCI device, which is a simple matter to resolve once the PCI device is working properly.  

Additional Information

This problem occurs because some BIOS manufacturers do not reserve the Interrupt Requests (IRQs) that are used by the PCI-bus. This means that other devices that do not use the PCI bus may try to use these interrupts. This will cause a conflict, and one or both of the devices will be unable to function until the conflict is resolved.

In Windows, the Device Manager will show the conflicting devices, and the Properties screen should confirm the IRQ conflict. This problem should only occur with a PCI and a non-PCI device on the same system, since two PCI devices would share the IRQ instead of conflicting.