How to Troubleshoot IRQ Conflicts

PCI cards are used to add sound or wireless support to the PC, while AGP cards are used to add graphic support.

Devices installed to the computer send interrupt signals to the processor through interrupt request lines, or IRQs. These interrupt signals tell the processor to stop what it's doing to allow a device to perform a task. If two or more devices attempt to use the same IRQ, hardware conflicts will occur, rendering the devices inoperable. Peripheral component interconnect cards can share the same IRQ without problem, but if a PCI slot is sharing the same IRQ as the accelerated graphics port or the USB controllers, errors may occur. Reconfiguring the PCI cards can resolve IRQ conflicts, as can enabling automatic IRQ configuration in the computer's setup program.

Things You'll Need

• Flashlight
• Phillips head screwdriver

Instructions

1. Turn off the computer. Disconnect the power cable and all peripheral devices connected to the PC.

2. Loosen and remove the screws that secure the case to the computer. Slide the case off the PC.

3. Set the computer on its side to that the expansion cards are at a 90-degree angle to the floor. Touch the chassis to ground yourself.

4. Shine a flashlight onto the motherboard and check the area near the back of the case. Read the labels on the motherboard to find out how each slot is numbered.

5. Loosen and remove the screws that secure the cards to the PCI slots if two or more slots are free on the motherboard.

6. Install the first card to the second slot; install the second card to the fourth slot. Make sure that the copper contacts are no longer visible, and then screw the cards into place.

7. Reassemble the computer case and reconnect all cables. Turn on the computer. If a conflict occurs with the second PCI card, install the card to the third or fifth slot after disassembling the case as instructed in the steps above.

8. Follow the instructions on the boot screen to access the setup program. Select "PCI/PnP Configuration" or "Advanced." Press "Enter" to open the menu.

9. Look for a submenu with "IRQ" in the name. Select the menu, and then press "Enter," if applicable.

10. Highlight "Resources Controlled By," and then use the "+" and "-" keys to set the option to Auto. If the option is not available, find an option with a name like "IRQ Slot 1" and follow the same instructions to change the setting to Auto. Repeat the step for each slot.

11. Press "Esc" to return to the main menu, or use the arrow pad to select the "Exit" tab. Go to Save Changes and Exit, and then press "Enter" to leave the setup program.

Tips & Warnings

• IRQ configurations can vary depending on your motherboard. Review your motherboard manual on your motherboard manufacturer's website for more assistance troubleshooting IRQ conflicts.