PC sound interference
March 17, 2004 1:43 AM   Subscribe

This is my first AskMe question: I've been annoyed for months by a sound problem with my PC. Simply put, my speakers pick up noise from the processor and hard drives that really offend my audiophile sensibilities. I think the cause is an IRQ sharing issue, but I'm not sure how to resolve it in Windows 2000. More inside...

So I look at my device manager and I see that no fewer than 8 devices are sharing IRQ 11, including my video card, ethernet card, audio controller (built-on motherboard, but I tried it also with a PCI soundblaster and got the same IRQ assigned), 3 USB controllers (wtf?), and my PCI IDE controller. Meanwhile, IRQs 2, 3, 4, 5, 7, and 10 are free. W2K grays out the option of changing the IRQs on any of my devices. My research online has turned up vague descriptions of how Windows 2000 "handles" IRQs automatically, but I haven't found any clear instructions on how and whether I want to disable this feature. Everything works, mind you... just a bit noisily since my speakers pick up this background noise.

If it's important, I'll mention that this is a P4 2.4GHz system. The motherboard is an admittedly cheap ECS that I got at Fry's with the purchase of my processor. I'd have replaced it long ago, but I don't relish the thought of reinstalling all of my software from scratch, which is almost always necessary with a mobo replace. I haven't really done any IRQ juggling since Windows 98, so thanks in advance for any wisdom and experience you have to share.
posted by Jonasio to Computers & Internet (9 answers total)
Processor/HD noise through speakers almost certainly isn't an IRQ problem, but a shielding problem. Your onboard sound and/or speakers probably aren't shielded that well, and are picking up EMI from your other components.

But, on the off chance that it's an IRQ issue, check your motherboard manual for details on how to manually set your IRQ for your sound controller -- probably via jumpers, or your BIOS. Change the IRQ to 7, reboot, and W2K should pick up the new setting.
posted by Jairus at 2:28 AM on March 17, 2004

If the disturbances in sound are in the form of clicks / pauses / skips during certain periods (ie. a lot of HDD activity, or reading from the CDROM) then IRQs are possibly to blame. I'm not sure how to fix this problem in Windows 2000 - I seem to remember being able to swap IRQs around in XP a while back.

On the otherhand, if the disturbances are actual sounds - hums, digital bleeps, crackles, then like Jairus said, it's not IRQs (although having everything on 8 certainly isn't efficient) but shielding. A good quality soundcard may fix the problem. However...One thing I'm wondering, do you get the exact same audio problems on both your on-board and your PCI soundcard? I would have thought this unlikely - what do you have your soundcard running out into? It may be an amplifier in your speakers that's picking up the interference from the PC.
posted by Jimbob at 4:20 AM on March 17, 2004

One quick fix, double click the speaker icon in your taskbar and mute CD Player, as well as anything else you don't use. I usually only leave Wave unmuted.
posted by signal at 5:15 AM on March 17, 2004

Response by poster: Thanks for the thoughts so far. Yes, I do get the same kind of noise from both my PCI Soundblaster sound card and my onboard sound. I should mention that the sound doesn't get better or worse when I fiddle with the software volume controls; it's all about the powered speaker volume control. I have a 3-speaker Altec Lansing set that I've been using for 4 years.

There's a constant hum and crackling noise accompanied by a pulse every second (the clock ticking, i presume) when I'm not doing anything. If my system is accessing one of the hard drives then I can hear that, too. But the most annoying is the processor noise: if I happen to view a web page with an animated graphic, I get a series of buzzes that correspond with the advancing frames of the gif.

I was asking about IRQ issues because that was the next step to try in my mind. I hadn't considered bad shielding. What would you folks recommend to fix a shielding problem?
posted by Jonasio at 11:31 AM on March 17, 2004

FWIW, it's also likely to be PCI bus bandwidth limitations. This thread on Anandtech forums has a bit of info. Video cards and hard drives take a lot of bandwidth, which can starve the bus.

If this is the problem, there are a few things to try. First, you can search for BIOS settings related to the PCI bus that could alleviate the problem. Second, you could get a different soundcard (people in that thread say Creative cards are picky about bus bandwidth). Third, if your motherboard has an AGP slot, you could pick up a cheap AGP video card, which would most likely eliminate what you call the "processor noise" (sounds more like video card traffic to me).
posted by whatnotever at 5:07 PM on March 17, 2004

Try turning off the hardware acceleration on your video card, if that helps, it's what whatnotever says.
posted by signal at 5:28 PM on March 17, 2004

Try a friend's pair of speakers, too. Just in case.
posted by armoured-ant at 5:45 PM on March 17, 2004

The sound issue is not caused by different speakers, I assume this because I have had this issue in different setups in the past. Here are a few ways I have fixed them:

First off, you are an audiophile but use an internal soundchip? More like you want to be. Understand that any real audiophile sound card is external from the computer on the basis of electrical noise and interference, although a 24-bit, 92khz (minimum) soundcard will sound very good. I personally recommend the Sound Blaster Audigy 2.

On my friends Gigabyte 81k1100, 16-bit AC97 sound chip, his RAID 0 caused sound issues but after removing the old drivers and updating them the poor sound went away.

Also, if you want to be sure its not an IRQ issue, go into your BIOS and manually set each device into its own IRQ. Windows will follow suit, although it may seem like windows is "reinstalling" the drivers after a reboot. Don't worry about this, of course.

Another sound (pun intended)recommendation is to make sure every driver on your machine is updated and current.

Did you know you can run two soundcards at once? Look at it this way: Onboard sound playing music at a party or public place (living room) and you can still play your games without disrupting the music.
posted by Keyser Soze at 7:07 PM on March 18, 2004

Oh yeah: If you get XP pro, ill hook you up with the "motherboard" patch so you can upgrade your pos motherboard.
posted by Keyser Soze at 7:09 PM on March 18, 2004

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