Fix Audio Ground Loop on Nvidia GPUs

[Plermpel]

Hello,

 

Since years I have the problem that Nvidia GPUs induce a terrible ground loop in my amplifier.

My 970 did it my 1080Ti did it and my 3080 and my 3090 does it.

I use a 24bit/192kHz eARC Extractor DIY modded to balanced 6,35mm balnced outputs (Which was unnescessary cause it didn't help...)

As soon as I touch my PC Case with the Shield of the HDMI Plug anywhere it's bare metal, or plug it in, I got the coil whine of the GPU amplified x50 in my livingroom.

 

Stumbling arround the Internet I found out that there is a thing like an earth off switch in some places of the world,

which made me die inside a little as an electrical engineer, but fixes the ground loop obviously...

 

DO NOT BREAK YOUR EARTH WIRE UNDER ANY CIRCUMSTANCES!

As long as you don't know exactly what you are doing, for example operating in a protective seperated circuit or with isolation montinoring.

 

Anyways it aroused my interest.

What I did is, I added a cheap foil capacitor (1nF) in series to the earth wire of my PC, just inside the wall plug, and I did the Job.

I tested my little janky cable, the RCD still trips on 25mA within half a second and the noise is gone.

 

 

If you try to do this, still be very careful, and only try it if you know what you are doing, if the Capacitor fails you still end up with no Earth protection!

 

Note:

If you live somewhere, where you don't have an RCD, your Earth wire still protects you from electrocution.

If everything done right there will flow a current back through your earth wire, which is high enough to trip the braker or kill the fuse, in case of a defective isolation.

It won't thou if you spill water inside a plug for example, so in best case if you don't have an RCD, get one!

[Boggy22]

Hey @Plermpel! I have this exact same problem. First had it with a Fiio e10K + Presonus Eris E5, but I fixed it by simply plugging the speakers in a different socket  that was ungrounded. However, 2 days ago when adding an Eris Sub8 into the mix (Fiio e10K > RCAs into Sub8's input > From Sub8 Output, RCAs to the E5 monitors) the same problem came back, only worse. If I plug the sub along the E5s into the same ungrounded socket, horrible hum. If I plug the Sub8 into the PC UPS sockets, I get rid of the hum, but I can still hear my GPU activity. 

 

Just listen to this, I simply started a simple "Render Test" in GPU-Z: https://www.dropbox.com/s/zevkjzs2nqoq1n8/16 Jun%2C 22.08.wav?dl=0

No, it's not Halloween

 

I ordered an iFi Defender+ which is yet to arrive, but if a capacitor in series with the ground wire works, I'd like to try that. The ground to this socket is routed from a different socket so I shouldn't have much trouble doing it. 

 

However before proceeding I wanted to make sure I got it, I should basically run the ground through the capacitor? Found 1nF/1600v, I'm guessing that should suffice? I also have access to higher capacitance (3-5-7nf), would those be better?

 

Thanks in advance!

Bogdan

 

 

[Plermpel]

Do you have an RCD?

The smaller the capasitance, the faster your RCD will trip 1nF is fine.

The Cap will block off everything but pure AC, which means, in case of a PSU failjure it will still trip,

also most RCDs aren't sensitive to DC anyways.