IRQ Conflicts

Windows Knows Best.

Even if you assign IRQs to the devices in BIOS settings, XP will override your settings, and put EVERYTHING on IRQ9.

IRQ steering is suppossed to take care of any conflict issues.

Is there some specific problem that you are having that you feel would be corrected by changing IRQ assignments?

On my XP Pro system, there are 8 devices assigned to IRQ 9, and I have not experianced any problems from the shared IRQ.

I originally thought a shut down problem was related to the shared IRQ, but it turned out that the modem and motherboard did not like each other in XP.

I do believe that there is a way to manually assign IRQs, but Microsoft Tech Support saves that as the last ditch effort to correct a problem.Chas

This may sovle your mystery.

It is a normal behavior for PCI devices to have IRQs shared among them, especially
on Advanced Configuration and Power Interface ACPI) computers/motherboards that have Windows
ACPI support enabled.

In Windows XP, Device Manager may list some or all of the devices on your ACPI motherboard
as using the same IRQ (IRQ 9). (To view the list of resources, click either Resources
by type or Resources by connection on the View menu). No option is available to change
the IRQ setting.

Windows takes advantage of the ACPI features of the motherboard, including advanced
PCI sharing. The PCI bus uses IRQ 9 for IRQ steering. This feature lets you add more
devices without generating IRQ conflicts.

Windows XP cannot rebalance resources in the same way that Microsoft Windows 98 does. (In Windows 98 You have the option to disable PCI Steering and manually configure resources). After PCI resources are set in Windows XP, they generally cannot be changed, and thats why your resources are greyed out.

If you change to an invalid IRQ setting or I/O range for the bus that a device is
on, Windows XP cannot compensate by rebalancing the resource that was assigned to
that bus. Windows XP does not have this ability because of the more complex hardware schemas
that Windows XP is designed to support.

PCI devices are required to be able to share IRQs. In general, the ability to share
IRQs does not prevent any hardware from working.

If I remember right, you've asked this question once before. As Chas and the other answer stated, XP assigns IRQ's to devices [regardless of whether or not you want it to]. This is something built into XP and is along the lines of doing away with PnP like the major brand computer makes do. This is supposed to be an advancement, so the average "Joe" doesn't have to know about assigning interupt requests, but what it really is a way to control piracy of MS software. XP is the first MS O/S that requires activation, takes an inventory of your computer hardware and if you subtantially change that hardware configuration reduces the functionality of the O/S until you reactivate it. Gone are the days of borrowing your friends copy of Windows to get out of paying for it or downloading it off of places like Kazaa or Morpheus IF you choose to use XP [be it the home version, Pro version]

Hello Friend,

These kind of problems i have been facing since 1995. Its very hard to give your desired IRQ and Base address for PNP Devices. The only solution i know is that, instead of starting installation after placing all the PNP deivces in the CPU, Try to install one by one device after intallation of any OS. I think this will resolve your problem.

One thing, it does not matter that few devices use the same IRQ because they are also using Base Addresses. It they are not showing exclamation sing or showing message like device is not working properly then you do not have to worry about anything.

I hope this will work.

Bye

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