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On my computer, when I plug my headphones into my rear headphone port I get great sound quality but when using the more accessible front panel headphone port I get a lot of interference.

After a bit of tinkering I found that the interference is caused by the cable from the front panel to the motherboard going right next to the graphics card. When the graphics card is under any kind of load (like even moving windows around) it causes interference in my headphones.

It's hard to move the cable right away from the graphics card as it goes from the bottom back of the motherboard to the top front of the case and doesn't have much slack. So is there any way to shield the cable from this type of interference?

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Thanks for the responses. I think the next step will be buy some ferrite beads or braided copper shielding to test with. It may be 2-3 weeks (on holiday from day after tomorrow) but I'll report back with the success. –  gacrux Jan 14 '10 at 2:22
    
I've gotten this on every desktop I've built over the past few years. My solution was to invest a few hundred bucks in an external USB audio interface. Not for everyone, but if you're interested in audio quality, it's really the best way to go. –  Archagon Apr 5 '13 at 17:30

5 Answers 5

Some people swear by ferrite beads for shielding. they cost about 5-10 dollars, and clip over cables.

On the other hand... i don't think that kinda interference is normal- video cards arn't supposed to be that noisy.

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+1 for ferrite. You see them on so many manufacturer-supplied cables because they work pretty well. –  Seth Jan 11 '10 at 22:33
    
I agree. It seems that if this was normal it would be a much more common problem. –  gacrux Jan 14 '10 at 2:20

If your graphics card is emitting electronic noise that's being picked up by the cable, it might help if you twist the cable a few times (I assume it's a ribbon cable that's amenable to twisting).

It might also be a ground problem. Check if the audio connector on the front panel is touching a metal part of the case, and make sure that the outlet you're plugged into is grounded.

Is this a home/custom built PC or a name brand?

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It's a custom build PC - Antec 300 case / Asus p755d pro mobo / Asus NVIDIA GeForce 9800GT 1Gb graphics card –  gacrux Jan 10 '10 at 21:19
    
I removed the front of the case - the headphone/mic port is enclosed in a plastic box (with 2 usb inputs) and there is a wire running out of the plastic box being grounded to the case. So I'm guessing the grounding is ok. The wires from the front panel to the motherboard are already in a single black cable so I can't test twisting them. Thanks! –  gacrux Jan 11 '10 at 0:09
    
Do you have a fan on your video card? Maybe it's the fan that's making the noise, not the card itself. If that is the case, I'm not sure what you can do about it... maybe get a new fan (?). You could try unplugging the fan for a few seconds with the headphones in and see if that makes a difference (so long as you're not in the middle of Doom3, the card shouldn't heat up that much in a second or two). –  Seth Jan 11 '10 at 22:23
    
Fyi, I have one of those aluminum iMac keyboards plugged into my Dell laptop. Sometimes touching the aluminum surface on the keyboard causes headphone noise. On some other motherboards, the problem is actually that the sound chip itself isn't shielded properly and picks up noise. You may just have to live with it. –  Seth Jan 11 '10 at 22:26
    
Yep, I have quite a big fan on my video card. Unfortunately the fan can't easily be unplugged whilst the card is on the motherboard so I can't test by unplugging for a few seconds. –  gacrux Jan 14 '10 at 2:18

You can buy some braided copper shielding at most electronics supply places (or, failing that, you can try some aluminum foil, although it won't be nice looking or possibly not as effective).

You're going to want to ground the shielding, as well as keep it safe from shorting the motherboard. I'd use a piece of shielding long enough to shield the cable, then secure the tail under a screw or other available place in the case. You may also want to use insulation of some kind (tape, etc) anyplace that the shielding might get close to the motherboard or similar areas.

It's also possible that the interference may be coming over the power system.

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I tested earlier (before posting my question) with some aluminum foil and it made no difference. But I didn't ground the shielding so perhaps that will help. –  gacrux Jan 11 '10 at 0:12
    
Grounding may help, and you'd see a lot better results most likely from copper braid shielding. –  phoebus Jan 11 '10 at 0:35

I fixed a similar problem by disabling the CD audio. I think in my case though it was because the internal CD audio cable was running next to the graphics card. So not sure if this would help in your case, but might be worth the try. It may in fact not be the other cable.

Muting CD Audio

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What helped me was to put the HDMI calbe in a slot further away from the audio cables of the onboard motherboard. Perhaps this may help your problem.

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