Help: Loud electric noise for PC speaker setup

[Bob is building]

Hi,

I'll be the first to admit I am absolutely clueless when it comes to audio. SO I'll try to best describe my issues so hopefully someone better informed than I can diagnose for me.

I bought some Logitech speakers - they work perfectly well on my PC's front audio jack. They are mains-powered. The issue is that when I plug them into the back (on the IO board) into the green 3.5mm jack labelled "audio out", the speakers immediately burst into this very loud buzzing noise which persists even when the PC is turned off. The only way to stop the noise is either to turn the volume down or to plug them into the headphone jack on the front. (or switch the speakers off at the wall).

Does anyone have any idea what could be causing this? The mainboard is a Gigabyte Z170 K3, which has decent onboard audio so this isn't EMI I'm sure- it's more or less brand new. There was no instructions so I'm in over my head.

Would appreciate any response,
Thanks 😀

 

[getochkn]

sounds like the grounding on the motherboard for the rear audio isn't good. Since it works on the front port, it's not a power issue in your house creating a ground loop, just that jack isn't grounded right. Short of playing around with a multi-meter and soldering iron to test it out, not sure what to say.

 

[Bob is building]

sounds like the grounding on the motherboard for the rear audio isn't good. Since it works on the front port, it's not a power issue in your house creating a ground loop, just that jack isn't grounded right. Short of playing around with a multi-meter and soldering iron to test it out, not sure what to say.

Thanks for the speedy response. I don't think that's it though. The noises coming from ground loop videos don't sound anything like mine. If I don't push the audio jack all the way in at the front it does the exact same noise.

Update: the speakers make the noise if they aren't plugged in at all.

Updated update: I just needed to push the bloody thing in harder 😀