Reallocate IRQ in Vista

  Esc4p3 12:20 14 Aug 2007

Following my previous thread at click here I still have some kind of conflict between my USB Modem & my Creative X-fi Extreme Audio sound card (a blue screen when sound and modem are combined).

I have uninstalled & reinstalled the modem countless times, trying several different Com ports for the modem (1, 3, 5, 10), so can anyone please advise what else I need to try.

1. Uninstall/update drivers for X-Fi?
2. Manually change IRQ to get rid of conflict (is this advisable or possible?)?

Also, the modem drops its connection quite frequently, and I am wondering whether the 2 are connected? When this happens, I have to disconnect the USB connection and reconnect it, otherwise it won't dial out.

The modem maker (Zoom) say that it is a conflict between the modem and the 'operating system' and I might try contacting Microsoft. 8-)

  Ashrich 12:53 14 Aug 2007

If your bios allows it you can give the PCI slot that your audio card sits in an IRQ of it's own , this will force the USB modem to look elsewhere for one it can use , try that .


  Esc4p3 14:00 14 Aug 2007


How do I know that the IRQ I allocate isn't being used by something else? Looking at my Mobo manual, there is a menu in the bios for "IRQ resources Setup", which could be what I am looking for.


  paul€ 14:56 14 Aug 2007

Usually using a different PCI slot will give the device a different IRQ.

Comm ports 3, 5, 10 will be virtual ports created from either comm port 1 or comm port 2.

If moving the card does not work alter the configuration in the bios.

Your IRQ's will be listed under all programs- accesories-system tools-system information-hardware resourses-irq's.

  Ashrich 16:02 14 Aug 2007

I believe that IRQ's are dynamic , if you force allocate one to a particular slot then the others will be re-allocated , but try the above answer first , try a different PCI slot , that would do the same thing .


  Ashrich 16:07 14 Aug 2007

The modem drop out could easily be Windows shutting down the USB port to save power , this power saving can be turned off in Device Manager ( Device manager/root hub/power management )


  Esc4p3 15:58 20 Aug 2007

Checked the USB root hub settings, and none of them are set to save power.

Still haven't got around to moving anything around yet, will let you know how I get on...

  Noelg23 09:31 21 Aug 2007

moving the sound card to another PCI slot will not change the IRQ. I had this problem with my X-Fi extreme music card. But mine wasnt to do with a modem, it was to do with crackling and hissing noise. In the end I moved the card to another PCI slot thinking it would change IRQs but it didnt.

So I removed the card and put my old one back in which worked no problem (after a 6mth absence). When I then put my X-fi card back in it was working ok but still hissing at times. then it stopped working altogether. So I have had it replaced by Creative since its under warranty still. Havent put in my PC yet as I might put it in my new machine that I will be building soon.

So, try first in the BIOS and if that dont work, then try a different PCI slot but this wont help. Your sound card will most likely be using IRQ 18 which is also being used by the USB root hub. I take it you have tried the sound card without the modem in the machine? u still get the same problem? if not then clearly IRQ conflict. but if u do, I would get the sound card replaced. HTH :)

  Esc4p3 08:45 22 Aug 2007

When I first got the PC everything worked fine, it was only after I put the modem in the machine that the problem started, I cannot have sound and modem at the same time.

Im fairly sure that the sound card is IRQ 17.

I was having a look on the Creative forums last night, which suggested that they are having some issues with Vista, particularly with their mediasource apps....

One thing I thought of last night is uninstalling and removing the card, and try the onboard sound (realtek) to see if that works....

  Ashrich 17:01 22 Aug 2007

Is the Realtek sound enabled as well as the Creative ? or does it turn off when another sound card is present .


  Esc4p3 08:57 23 Aug 2007

When I first got the PC, both sound options seemed to be active as the Realtek sound control panel was in the system tray, and was enabled in the bios. So I disabled it from the bios, and stopped the control panel running at startup.

I didn't install the modem for over a week after I got the PC. So my timeline was:

Days 1-4 (ish) both sound hardware enabled no problems
Days 4-7 (ish) Creative X-Fi only enabled
Days 7 onwards modem installed and blue screens

So I therefore assume that the onboard sound must disable itself?

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