[SpecChum]

I fear I’ve got a ground loop issue which seems to be caused by GPU activity.

I was originally using the line out of my Xonar DX into a Fiio E11k and didn’t really notice any issues but wanted an upgraded desktop amp, so decided to get a Little Dot I+ tube amp. However since doing this I get a slight electrical sound when moving the mouse and an awful screeching sound when using the GPU; playing games is a complete no go. Even the GPU test on GPU-Z causes it. Increased CPU load doesn’t seem to affect or indeed cause the interference; it’s only the GPU.

Both the amp and the PC are going into same extension strip and I’ve changed the power leads on them both to no avail.

At first I thought it was just EMI interference from my DX as it’s not shielded and sits right above the graphics card. I borrowed a SoundBlaster X-FI HD USB sound card and the interference is still there; obviously this connects to the PC via USB so at that point they share a common earth.

To rule out the Little Dot I+, which is a hybrid amp, I borrowed an all-tube Little Dot MkII and the interference is still there. Moving the Little Dot further away from the PC doesn’t help. Interference is happening whenever the RCA cables are connected – both amps are dead silent otherwise. To confirm this, there’s no interference at all when I plug my Little Dot directly into my Galaxy Tab S using the exact same RCA cables, so it’s definitely the PC.

Incidentally, I noticed last night that whilst I get no interference at all using the E11k when it’s plugged in to charge from an actual socket charger, I do get interference once the USB cable is plugged in to the PC; this, to me, pretty much confirms a ground loop issue on the PC.

Relevant specs are:
Corsair 230T case
MSI Z97 Gaming 5 motherboard
Sapphire Tri-X Fury at stock speeds
EVGA SuperNova G2 850W PSU

Anyone have any suggestions please?

 

[bigx5murf]

Does your PC have an optical out? If so, try it out on something, that shouldn't be affected by a ground loop.

 

[SpecChum]

Sort of, the Xonar does but then it has to go into the Sound Blaster which has to be plugged in via USB.
 
Just tried it for the sake of trying it...doesn't stop the interference.

 

[bigx5murf]

Do you have an onboard sound? If so, does it also exhibit the issue?

 

[SpecChum]

It does, yeah. Even the e11k does once I plug the USB in.

I've actually got an idea what it is now. The internal of my case is painted black, I suspect that's acting as an insulator for the motherboard ground.

 

[fluidz]

  Sort of, the Xonar does but then it has to go into the Sound Blaster which has to be plugged in via USB.
 
 

 
 
Which sound card do you have specifically? Can you link to it? The Soundcard you mention shows as having a Optical input.
 
Just to clarify, have you connected the optical out of your motherboard/Xonar into the input of the Creative card? 
 
Like this? Pc > Optical cable > Creative Hd > Rca cable to Amp > Rca cable to Speakers
 
As this should result in no ground loop. 
 
Connecting the computer to the X-fi HD external via USB isn't going to help the ground loop issue at all as the usb cable carries a current, optical should stop the noise altogether.
 
If you want to pair the Xonar with the Amp, you could always use one of these to break the ground loop (tried and tested with good results) > http://www.maplin.co.uk/p/ground-loop-isolator-vw43w?gclid=CI7a6NeCwcoCFQjmwgodNKIP9A
 
Btw my Case is a Haf X, also painted black inside so maybe you're onto something there. 

 

 

[SpecChum]

   
 
Which sound card do you have specifically? Can you link to it? The Soundcard you mention shows as having a Optical input.
 
Just to clarify, have you connected the optical out of your motherboard/Xonar into the input of the Creative card? 
 
Like this? Pc > Optical cable > Creative Hd > Rca cable to Amp > Rca cable to Speakers
 
As this should result in no ground loop. 
 
Connecting the computer to the X-fi HD external via USB isn't going to help the ground loop issue at all as the usb cable carries a current, optical should stop the noise altogether.
 
If you want to pair the Xonar with the Amp, you could always use one of these to break the ground loop (tried and tested with good results) > http://www.maplin.co.uk/p/ground-loop-isolator-vw43w?gclid=CI7a6NeCwcoCFQjmwgodNKIP9A
 
Btw my Case is a Haf X, also painted black inside so maybe you're onto something there. 

 

It's this one: http://uk.creative.com/p/sound-blaster/sound-blaster-digital-music-premium-hd
 
It does have optical in but it needs to be connected to a PC via USB to work; the ground loop is then created via this USB connection which then transfers along the RCA cables to my Little Dot amp creating the unwanted noise.

 

[bigx5murf]

So did you check your motherboard ground theory yet?

 

[SpecChum]

Not as yet no. It'd involve pretty much taking the while motherboard out.

I've been thinking about getting another case anyway so this might just be the excuse I need lol

 

[SpecChum]

I solved it by getting a usb isolator. It's limited to 24/96 but that's all I use anyway.

I can now use my little dot with games and music, hooray!

 

[fluidz]

Good to hear you solved it.

I bought a vlink 192 isolator to rid GL.

 

[bigx5murf]

Which isolator did you use?

 

[SpecChum]

Which isolator did you use?

It was a HifimeDIY one, only £30 but works perfectly.
 
It can only provide 200mA tho so it won't power everything; I suspect it'd struggle if I used the headphone out amp, but I just use line out and it seems fine

 

[oloendithas]

Hi,
Just resolved this nasty issue, thanks to guys from iFi, which ironically has a widest variety of groung filtering tool.
Here is a doc for one of those, which clearly with far red says "Adjust the audio system so that One and only One Ground/Earth connection is presented for the whole system".
As far as I undarstand, all connected devices share their Grounds by data cables and so, if they even more connect their Grounds in the wall socket, that's where the loop happens.
So I just sticked Ground contacts with an isolation tape on all power plugs except the PC one, and no more buzz/hum at all.