By Lou Dolinar
First in a series
Updated Feb. 14, 2006

As we spend more time on our PCs playing back music - or demanding audio for games - sound cards can experience problems that force us to work with a technology we'd hoped had gone away forever. Like Dracula, an ancient evil known as IRQ has risen from the grave to haunt the MP3 generation and users of high-end sound cards.

What's an IRQ, aka Interrupt Request? The basic deal is this: You plug a card into a PC; it needs to nudge the processor and say, hey, here I am, I need some computer time. The IRQ helps identify the particular card and makes sure, for example, that your sound card gets the processor's attention, as opposed to, say, your graphics card. In the old days, you used to have to set up this stuff in hardware so each device had a unique IRQ assignment, Nos. 1 through 15. Otherwise, you could end up with your graphics card trying to play back Britney Spears, which looks even worse than it sounds.

Windows XP was supposed to fix all that and usher in a new era of trouble-free computing. Plug and Play would sort out the IRQ mess, and devices could even share IRQs, Windows XP was so smart.

Well, like a lot of promises that emanated from Microsoft, things didn't quite work out that way. Most of the time, IRQs take care of themselves, but if you have trouble installing a new sound card, odds are that IRQ issues are to blame. If your music on your existing sound card is less than ideal, you may have a problem with IRQ assignments. Indeed, it's fairly easy to mess up a previously trouble-free installation, as I learned last week when Norah Jones and the Boudoir PC started acting flaky.

You remember the Boudoir PC? This is the silent music server I built that sits next to the lava lamp in my bedroom. It runs off a fanless VIA C3 inside a super-quiet Antec Sonata case and is equipped with an M-Audio Audiophile stereo sound card, not one of those tacky 43-channel gamer numbers.

Anyway, Norah was crackling, popping and dropping out while I was Web surfing. Once I figured out it wasn't a problem with the rip, it was time to start researching what was really going on. I ended up at www.musicxp.net, which has scads of excellent tips for optimizing sound playback.

In my case, the IRQ was the culprit. When I assembled my computer the first time, I used the BIOS setup program to disable hardware I was not using, a good procedure for everyone.

All of that freed up three IRQs, one of which Windows dutifully assigned to the Audiophile card. All was well for several months, until I decided to try to "optimize" the C3 to make it run faster. The computer wouldn't boot, and so I reset the BIOS to the factory default. This re-enabled all the stuff I'd turned off, at which point Windows, without me noticing, reinstalled the sound card, the serial port, the parallel port and the on-board sound cards. It may have even installed the lava lamp. I ran out of IRQs, and the Audiophile was sharing IRQ 9 with the graphics card. Thus the snap, crackle and pop.

I discovered this when I ran Windows System Information utility (see Programs:Accessories:System Tools) and looked at the IRQ data, which tells you the name of each hardware device on your system, and the IRQ that it uses and/or shares. No big deal, really; you can't hurt your PC by looking.

An easy fix, I say. So I restarted the computer, went back into the BIOS setup and disabled stuff I didn't want. Saved and restarted. Checked the IRQ assignment, and darned if the sound card wasn't still sitting at IRQ 9, along with the graphics card, even though there were three unused IRQs.

I forgot. Windows XP will assign new IRQs to a freshly installed device, but it won't change the IRQ of a device that's already installed. Indeed, as far as Windows is concerned, a shared IRQ for a sound card is just ducky. So how do you change the IRQ?

You pull the card, silly, the electronic equivalent of jump- starting a car with a dead battery. Turn off the computer, physically remove the card, restart the computer so it thinks the card doesn't exist, turn off the computer again, plug in the card, and restart. At that point, Windows will reinstall the card and give preference, you hope, to the unassigned IRQs, and set up your sound card on one of those. In my case, that's exactly what happened. Norah sounded like Norah again, and all was right with the world.

[NASSAU AND SUFFOLK Edition]

Newsday - Long Island, N.Y.

Author: Lou Dolinar

Date: Jan 23, 2005

Start Page: A.56

Edition: Combined editions

Section: MONEY & CAREERS

Text Word Count: 799

Document Text

(Copyright Newsday Inc., 2005)