I should know this..but (IRQ Question)

[Lotus 0]

I just noticed while going over my system information that IRQ 9 has a billion things on it. NIC card, Sound Card, USB Host Controller, ACPI-Compliant System, VIA USB Host Controller,.

 

Now I have never had to change IRQ's with Win2K as of yet. Using device manager I went into resources and it is all greyed out. How do I change IRQ's?

 

There are 8 listings in IRQ Conflicts for IRQ9

 

 

This might be half my problem with memory dumps and freezing on shutdown.

[Jerry Atrik 0]

search the forums about sharing of irq's

acpi shares em. disable that and u can change things

[packman 0]

There's nothing wrong with that, mate. With an ACPI-enabled computer, Win2K (or rather the BIOS) does often allocate several devices to just one IRQ. Resources are then handled dynamically.

 

On my previous Win2K machine, I too had several devices on IRQ9 and never had a problem with it. On my current machine, it being another Win2K machine, IRQs extend up to IRQ23 and I've got two devices on IRQ16 and two devices on IRQ19.

 

If you're really unlucky, you'll sometimes find that a particular device won't work in a shared environment (soundcards can sometimes be touchy). A lot depends on how often shared devices are actually in use.

[jmmijo 1]

Windows XP does the same thing, I think I have some devices using IRQ 29 or there abouts

 

You would have to change the HAL I believe, to a standard PC type which would then allow you to allocate manually, but I don't recommend this as you most likely don't need to do it. Also, if you're not having any issues with the sharing of said IRQ's then I wouldn't worry about it

[packman 0]

One of the problems that the convenience of USB technology has brought us is that for every USB port (or pair of ports) you have, there's usually a corresponding IRQ (I'm assuming here that the machine has been set up as an ACPI device, not a Standard PC [HAL configuring]). Normally, after the standard services and peripherals have been added to the machine, you're left with just two IRQs to play with. Thus, IRQs get used up very quickly. And because USB ports aren't themselves permanently uninstallable, you can't release their IRQs for use by other devices. You can disable a USB port but you can't uninstall it, because it'll simply get redetected the next time you boot [PnP]. (I've just been trying this on my own machine).

 

Disabling a port or a PCI card will show in Device Manager as a red cross. In Computer Management/Hardware/IRQs, the device and its IRQ will disappear from the listing - but will still exist! Thus, no reallocation of IRQs will occur and you might still observe sharing.

 

From experience with my own machine, re-positioning cards in the PCI bus can produce some swapping around of IRQs but it might not actually allow for any extra ones to be used. I'll keep you posted on that, as I'm still experimenting with mine at the moment.

 

Do remember that, if you uninstall or re-position a piece of hardware, you need to tell your BIOS about it, by entering the BIOS and setting Reset Configuration Data to Enabled and then booting into Windows again. You usually find that setting under PCI/PnP Configurations.

 

All in all, the PCI bus and the automatic allocation of IRQs is a bit of a pig's ear. It makes a nonsense of the provision of six PCI slots, plus one AGP slot as, in practice, you find you can only use some of those PCI slots if you're prepared to accept IRQ sharing.

 

Whilst on many systems, IRQ sharing might not be a problem, it'll depend (as I think the previous contributor stated) a good deal on what kinds of devices they are and whether at times they'll be used simultaneously.

 

The manufacturer of my motherboard, as with others, doesn't recommend changing the machine from an ACPI device to a Standard PC and assigning IRQs manually, as subsequently allocating resources can apparently be very problematic. It seems you have to reinstall the operating system, anyway (though don't quote me on that).

[packman 0]

I don't know whether this helps but, on my old Pentium 3 machine (which uses Win2K as well), four services/devices share IRQ9:

 

MS ACPI-Compliant System

Creative Platinum soundcard

AGP graphics card

USB Host Controller

 

The P3 machine is quite stable. It's not for ever bombing out or freezing or crashing or whatever. The BIOS and the operating system seem to cope okay with allocating resources to these devices/services.

 

The P3 machine, being older, allows for just 16 IRQs altogether. Hence the sharing of IRQ9.

 

With my current P4 machine, there's much the same AGP and PCI devices being used but I've added also a PCI video capture card. The BIOS and chipset, in this instance, allow for 24 IRQs, but four of those alone are taken up by USB 2.0 channels, so I still end up with IRQ16 and IRQ17 being shared.

[packman 0]

I've been experimenting with changing a few cards around in my main P4 machine. Result? Well, not unexpectedly, the net difference it's made is very little indeed. I've still two examples of where two services or devices share an IRQ. For instance, IRQ16 is used by both my AGP graphics card and the soundcard. Prior to this and prior to adding the video capture card, the soundcard had its own IRQ, as did the graphics card.

 

On the face of it, it looks a bit risky to have my graphics card and soundcard sharing the same IRQ. However, I had that situation, and more, with the other machine and that machine was pretty stable.

 

So, the answer seems to be that, if you ain't got enough IRQs for the devices and services installed, there ain't much you can do about it, on an ACPI-compliant machine.

 

The only real value in swapping cards around in the PCI slots, it seems to me, is in ensuring there's adequate clearance between cards, for cooling and for avoiding undue electrical pickup between the cards. Swapping 'em around won't necessarily throw up an extra IRQ from somewhere, though it might combine devices that are less likely to conflict.

 

Although the use of IRQ9 in Win2K for multiple sharing is often seen, PCs are sufficiently diverse that, really, no two machines are the same in the way that they allocate resources and hence IRQs. I think the method should be that you look at what the BIOS sorts out for you and, if you're not satisfied with the result, you should experiment a little.

 

In a more ideal world, we should have at least 30 separate IRQs at our disposal.