IRQ's

[babylon5guy]

Hi,
Is it really all right to have a lot of devices sharing one IRQ? I've read here a few times this is OK in XP, but I have ACPI, Radeon Card, USB ports, sound card, NIC, and RAID controller all on IRQ 11! What ticks me off is I have 4 free IRQ's, I don't know why they all have to use the same one. The reason I just don't like it as at times it seems to me it takes the hard drive takes a little longer than usual to fetch something, or the sound seems a little distorted at times, just little glitches that happen to devices sharing that one IRQ. I can just not get out of my mind that it is because they are all sharing that one IRQ. Any thoughts on this would be appreciated.
TIA

[reboot]

ACPI is what is allowing the sharing of the IRQ with no problems. If you really want to separate them, in XP, it's quite involved, and probably not worth the time.

[babylon5guy]

Thanks reboot that makes me feel better. It's just that in previous OS's it was a strict no, no. And everytime I look at all those devices on the same IRQ it makes me nervous. My PC does all in all seem to run ok, certainly better than it ever did on any other OS. But I do have the occasional freeze up at startup and a glitch here and there, but not all that aggrivating, but of course everytime it happens I think of all those things sharing the same IRQ. So it does help when someone with your expertise says it's ok. They sure must have improved ACPI in XP. I know if this happened in 98 I'd have a non functioning PC.

[crjdriver]

Windows xp [and win2k] are made to share irqs. Right now this computer that I am typing on shares five devices on irq11. There is no problem whatsoever. As Jim pointed out, it is a function of acpi; while it is possible to disable acpi without a reinstall of xp, I do not recommend it. Using the above mentioned procedure will result in having to reinstall one or more device drivers and may cause shutdown problems. In short if it works then I would leave it alone.

[reboot]

Previous OS's (Win9x based) have ISA support, and consider devices to be "Legacy". On older systems, each Legacy device needed it's own IRQ and memory addressing.
XP treats everything as PnP, allowing software to emulate any number of IRQ's (up to 255), one per device, no matter where they truly reside in hardware. This allows for the installation of far more devices in a system.
To get XP sorted, where each device has a unique IRQ, requires the removal of all devices, including ACPI, a reinstall, then adding each device one at a time afterwards.
You can FORCE XP to reassign IRQ's but going into Device mangler, System devices, PCI bus, IRQ steering, and disabling it completely. A great way to royally mess up your system.
In 98, it was sometimes necessary to do this to sort out IRQ's for conflicting devices, especially with winmodems. I do not recommend that you try it in XP.

[Iman74]

When dealing with IRQ's in NT, the best utility I found to use is going to Start Run and typing WINMSD

[babylon5guy]

Thanks guys, I feel much better. crjdriver sounds like you are in the same boat as me. It is good knowing someone else has the same thing going on with no problem. The little glitches I experience probably have nothing to do with my IRQ's. I shouldn't complain I have far fewer problems than I had with 98. Reboot thanks for the info on why XP handles the IRQ's better. You have all put my mind at rest, thanks again.

[sonnyb72]

I have my AGP card, RAID controller and Modem sharing IRQ 11 with no problems thus far.... I wonder why Windows XP seems to have such an affinity for no. 11?

Sonny

[reboot]

IRQ 11 is the most UNcommonly used IRQ in legacy systems.
If you look at the IRQ list, you'll see what each one has, and most of them are standard, and have been for a long while, keyboard, system clock, IDE devices etc. If the com ports are active in BIOS during the XP setup, then those are taken too, thus 11 is where all other PnP devices end up.