The Shortcut to Resolving an IRQ Conflict

This post was published 9 years, 1 month ago. Due to the rapidly evolving world of technology, some concepts may no longer be applicable.

During my hard drive adventures earlier in the day, I removed a PCI IDE-SATA card from an older computer, and replaced it with the PCI sound card that was previously in that slot. Computer started, and all was good – however, the audio was routed through the integrated sound instead of through the discrete sound card.

When I went to set the discrete sound card as the default audio device, the mouse froze for a second. This is one of those “you know you’re a geek when…” moments. Instinctually, I knew that there was an IRQ conflict (although, there were no error messages, etc. displayed at this point).

Right enough, rebooting the machine yielded a couple beeps and an error proclaiming ‘Resource Conflict for PCI device’ (with a slot number, and bus, etc). The slot, of course, corresponded to the sound card, but that was more a reassurance than anything else at that point.

Historically, I have found that IRQs are assigned at system boot, and can change when components are modified, especially, PCI components. The simplest solution, if possible, has usually proven to be:

  1. Remove the conflicting device
  2. Turn on the computer (new IRQs are assigned)
  3. Shutdown the computer
  4. Reinsert the conflicting device
  5. Turn on the computer (new, hopefully non-conflicting, IRQs are assigned)

It has been a rare instance when this has not resolved the IRQ conflict, and as long as one can identify the conflicting device, is typically a relatively easy fix.

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