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Long story short (and skipping over technical details, although I am happy to provide them should anyone be interested) I basically have a fairly severe problem with hiss and VRM noise being injected into my PC speakers, particularly in games. I have spent numerous hours looking into this with oscilloscopes and what not, and have managed to build dedicated processing circuits to get the speakers silent while idle, but although reduced, the noise is still an issue in gameplay.

ATM it looks like I have 2 options:
1 make a auxiliary supply for my sound card,an Asus strix Soar which uses a 6-pin PCIe connector for power to try further isolate the card from the other system components.
2 try to get the card outputting a balanced stereo signal.

option 1 is fairly easy technically, but will be annoying to actually implement in a usable manner. Since the card supports 7.1 surround, I see no reason why the eg the front and rear channel can be used to output a balanced stereo signal. Since there is less risk of breaking my sound card, I am leaning towards this option. Does anyone know how to do this?

I am also open to other options, however the standard stuff such as trying different power outlets and ground loops makes no difference. I can explain the technical reasons if anyone is interested. However I do not wish to buy extra gear such as USB dacs etc.
Thanks in advance
 

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Attack the source of the noise instead of trying to deal wit it after it's already present:

A piece of lead gutter flashing (or lead foil) on the side(s) of the PSU facing the motherboard?
Or just relocate the PSU outside the case and see if that helps.
Replace the video card(s) with a simple, cheep one and see if the noise stops.

Personally, I use and external USB DAC with a separate, linear power supply for it....I can put 1.2 KW into the speakers...silence with no source playing. But then, I'm a purist so just music (no gaming) and 2.1 audio only.
 

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Discussion Starter #3
Attack the source of the noise instead of trying to deal wit it after it's already present:

A piece of lead gutter flashing (or lead foil) on the side(s) of the PSU facing the motherboard?
Or just relocate the PSU outside the case and see if that helps.
Replace the video card(s) with a simple, cheep one and see if the noise stops.

Personally, I use and external USB DAC with a separate, linear power supply for it....I can put 1.2 KW into the speakers...silence with no source playing. But then, I'm a purist so just music (no gaming) and 2.1 audio only.
Theres basically 2 types on noise in my system. There is noise from the CPU VRM which occurs at idle (disappearing under load) and is common to both the ground and the signal line. I have filtered this using a unity gain differential amplifier. The GPU also creates noise however only when it is under load. This noise only occurs on the signal line AFAIK.

From the poking around with a oscilloscope I have done, I suspect the noise is likely coupling from the GPU through the power lines. I would therefore pick that running the soundcard on a USB mining style riser to fully isolate the cards power supply from the rest of the system and powering the card off a separate torroidal power supply and linear regulator outside of the case would isolate all the noise. Or at the very least adding a 4700uF cap or two close to the card would help.

I would go for a optical receiver or DAC etc to fully sort this, but a good quality one is well out of my budget. A USB dac would also work, but running my soundcard externally on its own PSU potentially with a ground loop isolator/high impedance earth reference to the motherboard should achieve the same result (correct me if I'm wrong) for a fraction of the cost.

I too run a 2.1 system, however I only use a 2.0 audio output and run active hardware processing and such to split off the subwoofer channel.
 

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Your solutions are far beyond my capability to critique.

I avoid the VRM/GPU problems by using software that copiers the digital music files to the memory sticks, hibernates the computer, and then streams the digital audio data to the external DAC (with it's own linear power supply). A amp meter I have on the computer reads 0.0 amps while the music is playing.
 

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Your solutions are far beyond my capability to critique.

I avoid the VRM/GPU problems by using software that copiers the digital music files to the memory sticks, hibernates the computer, and then streams the digital audio data to the external DAC (with it's own linear power supply). A amp meter I have on the computer reads 0.0 amps while the music is playing.
That definitely sounds like an interesting solution... Although not really much good in my case sadly. Thanks for your ideas, I'll let you know how I get on.
 

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I have a hard time beliving that asus would release a card that had that much of an issue with noise floor.

My ZXR was silent when running it on the board, and only developed a slight hiss when running it on a riser cable along with my GPU.

The quality of riser cable made a HUGE difference in noise floor, the $30 china special sounded like an old CRT while the lian li cables only have a slight hiss under full load.

I would vote ****y mobo or defective sound card before needing to fully isolate the card.
 

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I have a hard time beliving that asus would release a card that had that much of an issue with noise floor.

My ZXR was silent when running it on the board, and only developed a slight hiss when running it on a riser cable along with my GPU.

The quality of riser cable made a HUGE difference in noise floor, the $30 china special sounded like an old CRT while the lian li cables only have a slight hiss under full load.

I would vote ****y mobo or defective sound card before needing to fully isolate the card.
Its also down to a very high gain amplifier, although as you say, the motherboard may be faulty. It is an Asus crosshair VI hero. The onboard audio has the exact same issues. Although quite frankly I'm not sure whether I will be able to get a replacement particularly easily, however the audio does have a very high noise floor with every set of mains/usb powered speakers speakers I have tried.
 

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Discussion Starter #8
I have a hard time beliving that asus would release a card that had that much of an issue with noise floor.

My ZXR was silent when running it on the board, and only developed a slight hiss when running it on a riser cable along with my GPU.

The quality of riser cable made a HUGE difference in noise floor, the $30 china special sounded like an old CRT while the lian li cables only have a slight hiss under full load.

I would vote ****y mobo or defective sound card before needing to fully isolate the card.
Your solutions are far beyond my capability to critique.

I avoid the VRM/GPU problems by using software that copiers the digital music files to the memory sticks, hibernates the computer, and then streams the digital audio data to the external DAC (with it's own linear power supply). A amp meter I have on the computer reads 0.0 amps while the music is playing.
Update, running the card off an external (quite noisy plugpack) along with the filtering has greatly reduced the noise. I anticipate running the card off a proper linear power supply will further improve the results. Although that may create issues re my UPS.. might have to stick with a plugpack and add a few smoothing capacitors...
 

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Its also down to a very high gain amplifier, although as you say, the motherboard may be faulty. It is an Asus crosshair VI hero. The onboard audio has the exact same issues. Although quite frankly I'm not sure whether I will be able to get a replacement particularly easily, however the audio does have a very high noise floor with every set of mains/usb powered speakers speakers I have tried.

If it has the same issues as the onboard, I would lean more towards a faulty card. Most onboard audio I've used squeals like a stuck piga and a decent card has always been worlds better.
 

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If it has the same issues as the onboard, I would lean more towards a faulty card. Most onboard audio I've used squeals like a stuck piga and a decent card has always been worlds better.
Well running the strix soar off the PC's PSU along with everything else it does better than the onboard in terms of noise floor. Running it off a separate power supply it does incredibly well. At full GPU load and maxing the amplifier volume, the noise floor is less than what it was at normal listening volumes. Once I get a proper linear power supply sorted for it I expect it will be practically silent. Although I'll have to sort some way of getting round the fact I cannot run a transformer off my UPS and managing power outages...

Based off these results I would pick that the soundcard is functioning fine, as based off what I saw of the power supply noise, filtering it out would be quite a big ask. I will also be susceptible to noise issues more than most as I have a very high gain amplifier with relatively little noise filtering.

Thanks for your help.
 
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