Checked My IRQs - Some Shared Numbers - Question

I decided to check my IRQs in the Device Manager.

There were indeed a few that shared the same IRQ number.

I looked in the Windows help section on how to change them, and although it showed how to do it, the option to do so was greyed out when attempted.

I’m assuming that’s because in each case, there was ‘No Conflicts’ showing.

So does that mean just what it says?

Since there’s no conflicts, there’s no need to change or be concerned about them sharing the same number?
My understanding is that this is not ideal, and could cause issues.

Also, there were 3 that have a minus in front of the number.

I didn’t see that before when I had a look about 3 months ago. What might that mean?

Thanks Buds,


The issues with shared IRQs that existed with older Windows are in the past.

I believe that the OS now has efficient jump table redirection of interrupts to the correct handling routines that may have been held up in the past versions. In other words, they found out how to overload (share) IRQs without unnecessary performance hits.


usually not an issue at all any more.

Don’t touch it.

Cheers, Ernst

IRQs and sharing was an issue of the hardware bus design (ISA, EISA, MCA, PCI, etc.). ISA didn’t support it since it is an “edge triggered interrupt” but newer hardware architectures (as well as MCA, Microchannel, which is not so new) do support it because of the explosion in devices that need to be supported on a single motherboard now.

That’s just in case you’re curious.

Like others said, leave it alone. It doesn’t cause problems now.

Hello, do you know which Windows versions did this start to not matter anymore?


I’ll take your advice and leave it alone.

Thanks for the input/info Buds. Just what I was looking for. :wink:

As far as I remember, Win 7 on, but it’s all a bit vague. It could have been as early as Vista (which I had completely forgotten about until you asked this question!).

Ah thanks patanjali, I must read up on IRQ’s for older Windows versions that do matter…I’ve never bothered with it.

I am pretty sure the issues with IRQ sharing were a thing of the past when Vista came out. I never did Vista due to all the negative on it, but really Vista is a lot more like Win 7 than XP. The play nice version of IRQ sharing at the very least doubled the available number of them and as Larry points out really was needed. I have never taken the time to read up on how they pulled it off, but it is pretty seamless these days and works well.


IRQ sharing has only been an issue when whatever bus your soundcard was connected to shared its IRQ with other system critical devices like chipset or video, etc… . Sharing with USB hubs was not an issue.

Before XP, you could set IRQs manually to avoid this. XP introduced static IRQs that could only be changed by switching slots or removing cards, restarting system and re-installing cards to acquire a new IRQ. ACPI increased the number of IRQs and alleviated a lot of issues.

Never used Vista, so I can’t comment. W7 uses virtual IRQs IIRC which pretty much nulls any issues.

Switching my sound card to different PCI slots in a Win XP box is all I’ve ever bothered with. I can’t say that doing this has ever made any noticeable difference one way or other though. Looking at the IRQ sharing list never really made any sense to me, and appears to required deeper understanding to fuss with anything.