Help Troubleshooting A Problem - Noise in Surround Channels w/GeForce HDMI

[SuicideSquid]

Hi guys,

I'm pulling my hair out at a problem and hoping someone here can give me a suggestion. Here's the background:

We've been renovating our family home for the past two years and haven't been living there - we've been in two apartments over that time, but last week we finally got to move in. I wired the living room for surround sound and atmos, with four overhead speakers and outlets for three surround speakers. I'm currently running a 5.1.4 setup. All of the wiring in the house is new - all the in-wall speaker wire is 14-gauge, all the electrical wiring is brand new and up to modern code.

The setup:
Receiver: Denon AVRX4700H (preamp for front channels, power amp for overhead/surround channels)
Amplifier: Buckeye 6-channel Hypex NC252 (for front 3 channels)
Active Crossover: Dayton Audio DSP-408
Speakers: Totem Forest mains, custom centre and surrounds based on Totem Model 1 and Signature 1 for centre and surrounds, generic 6.5" ceiling speakers.
PC: AMD 3600 CPU, nVidia GeForce 4070 GPU, Asrock motherboard, 32GB RAM, 700 watt power supply.
TV: Vizio M65 2019 model

The problem:

Everything works and sounds great from any source but my PC. When I'm using my PC as the source, any time there's load on the GPU, even as simple as redrawing the mouse cursor, it creates a buzz. If I move the mouse around the screen it's like there's a mosquito coming out of my speakers. In games it can switch between no noise at all to all kinds of obnoxious noise depending on what's being drawn on the screen.

This was not an issue until we moved, that I'm aware of. But here's where it gets a bit weird - the noise is only in the rear and overhead channels. There's no noise in the front channels. If I switch from surround to stereo mode, there's no noise at all. I'm uncertain if this is because the front channels are being powered by the Buckeye amp, or if it's something to do with where the noise is coming from - prior to moving I was not using the Buckeye, I was using the internal Denon amplifier, and I was only running in stereo mode.

Here's what I've done to troubleshoot the issue so far:

1. Disassembled and cleaned the PC and ensured everything is properly seated;
2. Swapped HDMI cables from the PC to the receiver, and from the receiver to the TV;
3. Tried routing the HDMI signal from the PC directly to the TV with audio returning to the receiver via eARC - this got rid of the noise, but I think because it would only output a stereo signal when routed this way;
4. Tried swapping out power cables, as well as changing the outlets the PC and receiver are plugged into;
5. Completely disconnected and re-connected everything in my system, all speaker cables, RCA cables, power cables, HDMI, etc - and re-connected everything carefully to be as neat and tidy and avoid cables laying across each other as much as possible;
5. Moved the physical location of the PC relative to the receiver; and
6. Checked the outlets and power bar to confirm that everything's grounded properly.

I haven't yet had a chance to update my video drivers or mess with sample rate but that's the only thing left I can think of that might make a difference. If anyone has any other suggestions they would be VERY much appreciated because this is driving me crazy.

 

[staticV3]

Tried routing the HDMI signal from the PC directly to the TV with audio returning to the receiver via eARC - this got rid of the noise, but I think because it would only output a stereo signal when routed this way;

Your TV should be capable of outputting Atmos via eARC, once setup properly in the audio settings.
I'd first try getting that to work and seeing if the noise is gone.

If it's still there, then you'd have to play with grounding and isolation of your PC. Just like Toslink, an optical HDMI cable would prevent this kind of noise from transmitting to your AVR.

 

[SuicideSquid]

Your TV should be capable of outputting Atmos via eARC, once setup properly in the audio settings.
I'd first try getting that to work and seeing if the noise is gone.

If it's still there, then you'd have to play with grounding and isolation of your PC. Just like Toslink, an optical HDMI cable would prevent this kind of noise from transmitting to your AVR.

Turns out it was the bloody wireless mouse. In the move I swapped my old Logitech M510 for a G305. Swapped back, buzz is gone.

 

[SuicideSquid]

Well, bad news. Mouse was only part of the problem. When at the desktop, web browsing, or playing indie games, minimal noise after I swapped mice.

Last night I booted up a new game, Lords of the Fallen, that's GPU intensive and was bombarded with a crazy amount of noise from my surround/overhead channels. Buzzing, beeping, grinding - basically any time the computer's doing anything I'm getting noise of some kind of another, and it's probably ~70dB or so so very noticeable.

I disabled the Denon internal amplifier and I could still hear the noise coming out of the front speakers that are being amplified by the Buckeye amp, but that noise was around 20dB quieter than the noise coming through the Denon-amplified channels.

Tonight I'm going to try plugging in the PC with an extension cord to a different circuit entirely, and physically moving the PC to the other side of the room and plugging it in with a 12' HDMI cable to see if it's ground noise or physical proximity, both, or neither that's causing the issue.

Any other suggestions would be mightily appreciated. If I can't fix the problem I feel like my only options are "route the HDMI signal through the TV and get stereo only sound" or "buy another Buckeye 6-channel amp and live with quiet noise instead of loud noise".

 

[SuicideSquid]

If it's still there, then you'd have to play with grounding and isolation of your PC. Just like Toslink, an optical HDMI cable would prevent this kind of noise from transmitting to your AVR.

I wasn't aware fibre optic HDMI was a thing - very cool. Just had a quick look and they mostly seem to be available in longer runs - do you know if anyone makes a short (3-6') fibre optic HDMI cable? I don't really want a 30' coil of HDMI behind my stereo console. [edit] Never mind, I found one that's 10' long. May give that a try if tonight's troubleshooting doesn't work.

 

[staticV3]

Any other suggestions would be mightily appreciated.

An optical HDMI cable or Toslink cable would electrically isolate the PC from your audio system and would prevent any electrical noise from being transmitted to it.

 

[nutzandvoltz]

Well, bad news. Mouse was only part of the problem. When at the desktop, web browsing, or playing indie games, minimal noise after I swapped mice.

Last night I booted up a new game, Lords of the Fallen, that's GPU intensive and was bombarded with a crazy amount of noise from my surround/overhead channels. Buzzing, beeping, grinding - basically any time the computer's doing anything I'm getting noise of some kind of another, and it's probably ~70dB or so so very noticeable.

I disabled the Denon internal amplifier and I could still hear the noise coming out of the front speakers that are being amplified by the Buckeye amp, but that noise was around 20dB quieter than the noise coming through the Denon-amplified channels.

Tonight I'm going to try plugging in the PC with an extension cord to a different circuit entirely, and physically moving the PC to the other side of the room and plugging it in with a 12' HDMI cable to see if it's ground noise or physical proximity, both, or neither that's causing the issue.

Any other suggestions would be mightily appreciated. If I can't fix the problem I feel like my only options are "route the HDMI signal through the TV and get stereo only sound" or "buy another Buckeye 6-channel amp and live with quiet noise instead of loud noise".

Its coming from your computer.
The lowest noise situation would be the computer plugged in the same power strip as the denon receiver.
Changing the computer power supply sometimes fixes this.
But all audio jacks on the computer and usb power is noisy by nature because the power supply in computers have noise on their grounds. And there is little you can do about that other than using a better connection (spdif optical or using something else like audio over ip (dante avio + virtual sound card))

 

[staticV3]

do you know if anyone makes a short (3-6') fibre optic HDMI cable?

Here's one I found on Amazon: https://www.amazon.de/Glasfaser-High-Speed-Glasfaserkabel-kompatibel-Projektor/dp/B09YPRB8T8

Though what's strange is that they show what looks like a regular copper cable in their marketing material:

 

[SuicideSquid]

Its coming from your computer.
The lowest noise situation would be the computer plugged in the same power strip as the denon receiver.
Changing the computer power supply sometimes fixes this.
But all audio jacks on the computer and usb power is noisy by nature because the power supply in computers have noise on their grounds. And there is little you can do about that other than using a better connection (spdif optical or using something else like audio over ip (dante avio + virtual sound card))

Obviously it's coming from the computer.

The computer has been plugged into the same power strip as the receiver. I am not using an analog or USB out - I'm using audio over HDMI from my GeForce graphics card, as stated in the original post. As also stated in my original post, when I had this same graphics card plugged into the same receiver at two different prior apartments, I did not have a noise issue so no, there is nothing inherent in PC audio or this particular setup that means I'm going to hear distracting noise at all times.

The issue to determine at this point is whether the noise is EMI being transmitted through the air, or a grounding issue. If it's EMI then hopefully relocating the PC a couple feet away will fix the problem, as one of the changes I made when we moved was relocating the PC from about 3' away from the receiver to sitting adjacent to the receiver. If it's a grounding issue then I'm going to try plugging into a different circuit, since that's free, and if that doesn't solve it, I'll give staticV3's suggestion of a fibre optic HDMI cable a go.

 

[SuicideSquid]

All right so I finally fully fixed the problem.

Noise was getting in two ways!

I plugged the computer in with a two-prong power cable with no earth. Still noise. Realized the PC was still plugged into the Dayton Audio active crossover w/USB. Unplugged the crossover from the PC.

Noise gone!

Plugged the PC back into the wall with a proper three-prong power cord.

Noise returns!

So to fully get rid of the noise I have to plug the system in with a two-prong cable AND unplug the USB connection to the Dayton active crossover.

Ugh. At least it's fully solved now.

 

[GXAlan]

So to fully get rid of the noise I have to plug the system in with a two-prong cable AND unplug the USB connection to the Dayton active crossover.

Ugh. At least it's fully solved now.

Now you know it’s a ground loop.

What you can do, is to try a Panamax power conditioner, not because you need power conditioning but you can have a ground wire from the Panamax to the phono ground lug of the Denon. Then everything plugged into the Panamax will be grounded to the same potential.

Running XLR from a floating ground Yamaha CX-A5100 to a three prong active speaker has noise which is corrected when I ground the Yamaha to the same ground as the speaker. You would think that the XLR cable would eliminate the ground loop, but it didn’t. A simple wire did.

Edit: There are plenty of other ways to ground the two-prong Denon to the rest of your system -- but Panamax is a simple UL Listed solution. You never know how good/bad your home wiring is unless you did it yourself and the random wires off Amazon are of unpredictable quality.

 

[nutzandvoltz]

All right so I finally fully fixed the problem.

Noise was getting in two ways!

I plugged the computer in with a two-prong power cable with no earth. Still noise. Realized the PC was still plugged into the Dayton Audio active crossover w/USB. Unplugged the crossover from the PC.

Noise gone!

Plugged the PC back into the wall with a proper three-prong power cord.

Noise returns!

So to fully get rid of the noise I have to plug the system in with a two-prong cable AND unplug the USB connection to the Dayton active crossover.

Ugh. At least it's fully solved now.

Interesting.
So in the previous place this was not an issue, correct?
If so, the first thing you should look at is the wall outlets. remove the cover, and see if they put the wire on the screw terminals, or just stabbed the wires in the back. The way we want them is on the screw terminals because the other way has issues at times maintaining a low impedance connection in the outlet.

This would be the first logical thing to look at.

 

[SuicideSquid]

Edit: There are plenty of other ways to ground the two-prong Denon to the rest of your system -- but Panamax is a simple UL Listed solution. You never know how good/bad your home wiring is unless you did it yourself and the random wires off Amazon are of unpredictable quality.

It's brand-new wiring that cost us a lot so one would hope it's good. But I'm definitely not dropping several hundred dollars on a line conditioner, I'll run without an earth on the PC for now and see if the fibre optic HDMI isolates the computer from the rest of the system sufficiently to re-ground it.

Interesting.
So in the previous place this was not an issue, correct?
If so, the first thing you should look at is the wall outlets. remove the cover, and see if they put the wire on the screw terminals, or just stabbed the wires in the back. The way we want them is on the screw terminals because the other way has issues at times maintaining a low impedance connection in the outlet.

This would be the first logical thing to look at.

I'll give this a look, thanks.

 

[GXAlan]

It's brand-new wiring that cost us a lot so one would hope it's good. But I'm definitely not dropping several hundred dollars on a line conditioner, I'll run without an earth on the PC for now and see if the fibre optic HDMI isolates the computer from the rest of the system sufficiently to re-ground it.

There are definitely deals on eBay and Reverb. You just need the cheapest one with a grounding lug. Again, I can only recommend something UL-listed with a ground lug where it's easy to run a bare wire from grounding lug of your power conditioner to the grounding lug of your AVR.

I am not an electrician, but you may want to talk with one about pros/cons of using a portable GFCI outlet to provide safety when running your PC without earth ground.
I am not an electrician, but you may want to talk with one about pros/cons of using a grounding cable from Amazon that you can plug directly into your wall outlet and attach to your Denon.