PC - DAC ground loop (GPU culprit)

Hi to all. I noticed a ground loop between my PC and my DAC. It’s pretty much exactly the same described in this video (skip to 11:28). It also responds to locking fps and changes pitch accordingly.

This has been reported extensively across various forums. I’ll just link to one nvidia thread, but I also saw it for AMD cards: {{MetaTags.og.title}}

I bought an IFI idefender, but not only did it not break the loop, but it also introduced a new hissing sound, so it’s a no-go for me. I tried disconnecting everything except the PC, the DAC and the amp, and the ground loop persists. It even happens with the DAC disconnected from the current. Connecting the DAC to a laptop (and using the laptop’s battery) doesn’t produce the ground hum, so the DAC is not defective.

The only thing that breaks the loop is lifting the ground from either the PC or the power conditioner where all my audio stuff is connected to (I did try other extension cords with same results). I did try different power sockets in the room, same result.

Other than permanently lifting the ground from my audio gear, do you guys have any other suggestions?

Note: changing to optical input is not an option, I bought a USB dac to use it by USB.


  • PC: i5 8600k + asus z370-a prime + nvidia EVGA 1070 + 2x8 gb ddr3000

  • Audio setup:

– Audiowalle TP1000 power conditioner (AKA fancy power extension cord)

– Vincent sv237-mk

– DAC: SMSL m500

– KEF R300

Welcome, Dexter_prog!

Ground loops are difficult to eliminate. Typically connecting all equipment to the same electrical circuit helps. Are the PC and the audio equipment on the same circuit?

Forgot to mention, tried plugging all in the same circuit (PC and computer monitor to the TP1000) and it didn’t help.

Have you pulled the GPU to find it doesn’t occur?

Yes, I tried with the onboard GPU. It happens at a much lower volume, almost inaudible.

This is odd. Plug everything into the same strip, hum remains. But lift the ground on PC or conditioner and hum goes away.

What happens when you lift the ground is ground current is forced to go through the unlifted path. When you plug everything into one strip, a similar situation occurs in that the ground is now shared.

Does the hum change in character between these two situations?

It’s a bad idea to lift the ground pin if it exists. The unit may become live and dangerous if a component fails.

I suggest you check the power cable to the pc, its 90% likely there’s no ground wire or ground pin. In some cases this means noise has nowhere to go but through to the audio system.

Try adding a ground wire from the chassis to the mains ground. That might mean changing the cable and plug with an earth pin. Or you could run just an earth wire from the chassis to a new plug. Or Jplay sell a grounding cable for a lot of money.

didn’t even know what Jplay is but their FAQ is hilarious. It’s basically “it’s better because we say so” http://www.jplay.eu/faq/

Yes, but it’s not just hype…

Did you try my grounding solution?

I didn’t quite undedrstand how to do what you mentioned, haha.

PS: ferrite chokes didn’t work either.

The simplest way to make a grounding cable is:

  • Get a mains plug with 3 pins and connect a wire to only the earth pin.
  • Connect the other end of the wire to bare metal of the computer chassis. You can use an existing chassis screw to secure it.
  • Then plug the cable into the mains socket.

If this doesn’t work the problem could be elsewhere. You could try grounding the other devices in your audio setup in the same way.

I hope this works for you.

Gonna try that whenever possible.

I’ve just tried a cheater plug with where the amp is plugged, and it removed the hum. Could it be that the amp is the problem? Or is there any more logical electrical explanation? I guess the hum was always there and this amp just amplifies it even more??

Did you read this?

Another source of hum is unshielded interconnect cables hanging near power cables.

I have had a very frustrating multiple years dealing with the DirectStream introducing a very loud and unlistenable ground hum into my Conrad Johnson Premier 350 amplifier. Lots of experiments and plugging/unplugging every permutation of component/cable, and it always came back to my DS Sr as the root cause of the ground hum in my system. Lifting the ground on my amp removed the hum but was very detrimental to sound quality… loss of warmth/naturalness to the sound… PRAT went away. Lifting the ground on the DS Sr. produced similar harshness/digital-brightness to the sound. I ultimately solved this the best I could by introducing a high-wattage 8 ohm resistor in-line with the ground wire coming from the amplifier’s case to the ground pin on the IEC connector. The resistor allowed the amp to remain grounded and keep the sound warm/natural while providing just enough resistance to stop the ground hum.

That’s quite an innovative and clever solution.

Thank you for posting this. We need to remember this fix if the issue comes up again.

Excuse my ignorance, in order to to that, do you have to open the amp and do this internally?

Yes. Typically you’ll see a ground wire screwed to the inside of the case that connects to the ground plug on the IEC power connector on the case. You basically change it to be case-> ground wire- >resistor -> IEC ground plug. The number of ohms needed to stop the hum should be as low as possible. 8 ohms solved my hum, more or less Ohms may be required in another system. You’ll want a resistor with the lowest ohms that works and with enough watts capacity to be able to safely handle a short. Connecting an external ground wire from your case to a shared ground is another possibility to fix a ground hum, but that approach didn’t work for me.