PC sound interference.

eeBoBoBo

Active Member
Hello all.

I have a sound interference issue, which is driving me mad. Let me elaborate.

I won’t go into detailed PC specs as I’m not sure that’d be necessary, but this is it in brief:

i5 10600k

MSI Z490 Gaming Edge MB.

RTX 3080

EVGA 750W SuperNOVA G2 PSU.

I recently bought a new VRR TV (75” Q95T, which is brilliant by the way) for the living room, so I decided to run some cables to it, from my bedroom above, where my PC lives. I ran 5 meter lengths each of HDMI (into the One Connect box), optical (into my Rotel processor) and a USB cable, which connects and extends via a powered hub in the living room, to which I have a keyboard, mouse, two game controllers and sometimes headphones connected. I quickly discovered that I have some awful interference when gaming, and also at other times, even when component stress is very low. I use Launchbox, for example, which is front end software primarily for use with emulation. It’s certainly not remotely stressful for a system like this, but I get variable buzzing and interference when scrolling through games on that. If I load up World of Warcraft, then turn the game audio down in the interface and just move the camera around, it sounds awful, again with variable noises etc coming through my speakers.

I usually have this PC connected to a Denon surround amp in the bedroom, also via a shorter optical cable which I just unplug and change for the newer longer cable, and I have no sound issues at all with that. That being the case, I initially laid the blame on one of the cables with them being the new addition. To test the cables further, I connected all three of them to a PS4 Pro, only to find that all three cables work flawlessly, with no sound issues whatsoever. So that 99% rules a bad cable out I concluded.

Sound duties on my PC were being carried out by the onboard audio, so to eliminate that from the equation, I bought a Sound BlasterX AE-5 (disabling the onboard audio it goes without saying), hoping that would save the day, especially with it being so well reviewed too. However, no, it was just the same. I then tried an external DAC (Sound Blaster X3) but again, no difference.

Another thing is that if I use my headphones on the hub in the living room to pick up the sound through USB, the sound is perfect.

At first I was wondering if it was the video card, as I’ve read about people having issues with Nvidia GPUs causing sound interference, but then, surely I’d hear that when the sound is sent to my Denon amp. Or if it’s some kind of power issue. I’m aware of ground loop problems (which I know little about) but any forums I’ve read don’t quite hit the mark with exactly what I’m experiencing, with a lot of examples not quite being the same as mine.

Has anyone had this same issue or something similar?

Any advice would be great.
 

Kapkirk

Active Member
The video signal is probably to blame and is somehow causing RF to get through the HDMI lead or connection.
Are you saying that you are routing the sound and video from the pc to the TV and the interference is coming from the tv speakers? and not the Denon amp which uses optical?
 

eeBoBoBo

Active Member
Hello.

No, only the video is being sent on HDMI (I disabled the Nvidia audio devices in Windows). Audio via optical, to my processor, then power amp, then into my speakers. No audio through the TV itself.

So, at any point, either while in use upstairs or down, it is sending audio via optical. Either through one running into the Denon in the bedroom, or I unplug that and use the new, longer cable running downstairs into the Rotel processor. Sound when plugged into the Denon is perfect.
 

Kapkirk

Active Member
Hmm that is very interesting, you should not be getting ANY rf interference over optical.
I am wondering if the graphics card is producing some rf or spurious signal out to the long HDMI cable which is acting as a giant antenna. With the amp turned on and with the optical lead pulled out do you still here the noise?
 

eeBoBoBo

Active Member
Yeah, I was thinking that after my last reply. Probably one of the first and most obvious things I should’ve tried to be honest.

Just finished a night shift though, so I’ll give it a try later and report back.
 

EndlessWaves

Distinguished Member
(disabling the onboard audio it goes without saying)

Did you also check it was 100% soundblaster compatible?

On a more serious note it's hard to spot a potential culprit at this stage so it's worth trying the various options and configurations you haven't tried already (audio output to the TV, new optical cable on old amp).

Beyond that, what's your audio output format from the PC? Standard stereo PCM? Or is it set up to do on the fly AC-3 encoding?
 

eeBoBoBo

Active Member
Hi again. I ended up busy last night so couldn’t check this out, but after trying this morning, I can confirm that if I unplug the HDMI cable, the sound issues stop.

Not really sure what to do with that. I initially wondered if it could be because they all (HDMI, Optical and USB) ran alongside each other, but as I say, when connected to the PS4, they’re perfect.

I’m starting to think it could be the problem I’ve read about that others have had, in that the GPU itself is the culprit. If so, does anyone know a fix for this?
 

next010

Distinguished Member
I’m starting to think it could be the problem I’ve read about that others have had, in that the GPU itself is the culprit. If so, does anyone know a fix for this?

I've no idea if will actually work, there are claims that the interference cannot travel over plastic/fibre, you could try a fibre optic HDMI cable but some part of that might have a wire component that makes the connection ?

You can see an 5 years ago thread on nvidia forums with various solutions people have used to counter interference from GPU, one person did this.

I was able to kill it by using an rca to optical converter to a fibre optic cable and an optical to rca converter. It breaks the electric connection.
 

strangely tim

Well-known Member
When I install a lead these days the first thing I do is add a ferrite bead/clip to it even if it may not be necessary its just a habit now and the ferrite is cheap enough.

I'm a radio ham and have found all sorts of home appliances and leads giving me grief in terms of interference from fridges, TVs to PC/laptop power supplies to computer audio adapters to a phone charger and microwave oven. I bead everything and at best it helps a lot and and worse its done no harm.
 

eeBoBoBo

Active Member
First of all, thanks to everyone for the replies and suggestions.

I think I’m going to have to just read up on this on other forums now it seems I’ve isolated it to the GPU. I should’ve tried the disconnecting of the HDMI early doors it seems, at least then I’d have known it was related to that. Frustratingly, I didn’t try the external DAC on a powered hub, instead just connecting it to the I/O. I wonder if that could’ve worked, as I’ve seen that it worked for another person on the link that next010 provided.

Although, to counter that again, I don’t get this when I run the audio through the Denon amp that sits in the same room as the PC. However, the video duties when in the bedroom rest with Display Port. Hmm. I’ll try a short HDMI to the monitor in my bedroom, I think. Sorry, just thinking as I type.

I thought about ferrite beads, but opinion seems to vary on their effectiveness on HDMI cables. I threw a decent amount of these away recently as they’d been in my drawer, unused for about ten years. Always the way…

I’ll have a deeper look at the fibre HDMI cables too. That’s something that sounds like it could work.
 
Last edited:

ChuckMountain

Distinguished Member
I’ll have a deeper look at the fibre HDMI cables too. That’s something that sounds like it could work.

Most long “fibre” cables are hybrid these days so contain copper wires and shielding, only the video and audio are carried over the actual glass fibre. The audio and video on HDMI are intertwined anyway. Therefore the interference might still be present on a hybrid fibre cable.

You might also have a faulty HDMI cable so if it doesn’t appear on shorter cable, try replacing cable with another one, and possibly different brand
 

jimscreechy

Active Member
My guess would be that the long HDMI cable is generating the 'noise' and feeding it back into your system. The tendency is to think that noise in the signal just goes one way - to the amp - and since your not using that cable for the audio source it won't cause a problem... and strictly speaking it shouldn't and you have done the right thing.

However the truth is interference or 'noise' will going in any direction it can (which is one of the reasons why grounding is such an important aspect of system design... but that's another topic) at any rate, even disabling the sound device may not necessarily decouple the noise from the audio 'circuits' that are picking it up back at the PC. The HDMI cable is still connected and the generated noise is still there and getting routed not through the optical cable, but the circuits that support it. Remember the optical part is only really the last leg in the signal transmission, all the supporting electronics are still wired.

I'm not sure there is a fix for this outside running a different physical path that my be less inclined to suffer from this interference. Long cables are always subject to potential issues but you may be able to do something at the pc to 'break' path back into your system.

At any rate I think this is more likely to be the cause of the problem
 

eeBoBoBo

Active Member
Okay. Again, thanks for the input.

Work has dictated that I’ve not been able to give this much attention since my post, but today I ran an extension cable from the living room, where my processor and power amplifier etc are plugged in, up to the bedroom, so I could power the PC from the same outlet.

Hey Presto, no interference at all. So, I suppose that tells us that it is a grounding issue after all. That was an easy thing to check in the end, but this issue was new to me even though I now know it’s a common problem.

With that in mind, are there any good devices / fixes that folk use before I start getting a spark involved?
 

jimscreechy

Active Member
No, unfortunately not, or at least not that I know of. Though I certainly appreciate your pain. Perhaps others have some suggestions but If I think of anything...
 

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