That is a cool setup for a slot 1 system. The Yamaha sound and ATI graphics.
But, I don't like the fact too much that the sound chip is that far away from the backplate. Will have some very practical reasons on such a condensed layout, but somewhat bad design.
So, all kinds of shit going on between there. A PCB line of 20 cm is basically one big antenna as it is not shielded.
Put your cellphone anywhere near it, send a text to yourself, if the system broadcasts all that live, it's probably not about any caps.

What back end do you use there, headphones, active speakers, amp?
Does that thing have both a line out and headphone port? Don't think so, most had three 3.5 mm ports, being line out/headphones, line in and microphone.
Addon ISA cards have amplified headphones out and line level out or some jumpers to disable the amplifying between those.

My point is: Any amplification that results in an audible level with anything, including headphones, does amplify the slightest distortion or noise.
E.g. I have a fancy brand pair of 90s "monitor style" active speakers here. So, they're not cheap garbage, but, at higher volume, they clearly pick up a certain AM radio station. 😜

Ideas:
- Is there a setup software or mixer specifically for the chip? Try disabling anything that says "amplify" or "gain".
- disable any line in, aux in, CD in and especially, microphone in in the mixer.
- try a different PSU

Weird idea: It could be that a bad switching PSU has more distortions with low load. You could try elevating it to higher load by simply attaching some load to the system, like heavy VGA, drives or even just a lamp to the 12 V.

Other weird one: The XG is a big mother. Someone here will know, does it emit analog audio itself, without any more DSP or AD changer behind it? If so, find out the pins, improvise a shielded line cable to those directly, bypassing the whole mess behind that, compare.

I'm impressed how good the documentation is, page 22:
https://www.elhvb.com/mobokive/archive/intel/ … EX_70100301.pdf

Cuttoon wrote on 2022-05-06, 00:21:

That is a cool setup for a slot 1 system. The Yamaha sound and ATI graphics. But, I don't like the fact too much that the sound […]
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That is a cool setup for a slot 1 system. The Yamaha sound and ATI graphics.
But, I don't like the fact too much that the sound chip is that far away from the backplate. Will have some very practical reasons on such a condensed layout, but somewhat bad design.
So, all kinds of shit going on between there. A PCB line of 20 cm is basically one big antenna as it is not shielded.
Put your cellphone anywhere near it, send a text to yourself, if the system broadcasts all that live, it's probably not about any caps.

What back end do you use there, headphones, active speakers, amp?
Does that thing have both a line out and headphone port? Don't think so, most had three 3.5 mm ports, being line out/headphones, line in and microphone.
Addon ISA cards have amplified headphones out and line level out or some jumpers to disable the amplifying between those.

My point is: Any amplification that results in an audible level with anything, including headphones, does amplify the slightest distortion or noise.
E.g. I have a fancy brand pair of 90s "monitor style" active speakers here. So, they're not cheap garbage, but, at higher volume, they clearly pick up a certain AM radio station. 😜

Ideas:
- Is there a setup software or mixer specifically for the chip? Try disabling anything that says "amplify" or "gain".
- disable any line in, aux in, CD in and especially, microphone in in the mixer.
- try a different PSU

Weird idea: It could be that a bad switching PSU has more distortions with low load. You could try elevating it to higher load by simply attaching some load to the system, like heavy VGA, drives or even just a lamp to the 12 V.

Other weird one: The XG is a big mother. Someone here will know, does it emit analog audio itself, without any more DSP or AD changer behind it? If so, find out the pins, improvise a shielded line cable to those directly, bypassing the whole mess behind that, compare.

I'm impressed how good the documentation is, page 22:
https://www.elhvb.com/mobokive/archive/intel/ … EX_70100301.pdf

The tech manual for the motherboard is great, it's helped me with alot of detailed info about the parts and layouts, but no schematic diagrams to see how the caps and components are laid out 😜
You bring up some good points. The back ports are speaker/phones, line out, mic in. While in Windows all the sliders on everything turned down in mixer, but still get noise as long as the master slider is above zero. first sounds like a feedback blip then turns into crackling and static. sometimes drops out completely and comes back. In dos mode even running the sound util and setting everything to low i still hear it. I'll add this is with no add-in cards and all onboard ports turned off except for audio.

Regarding the PSU. It has been replaced at some point. there is a 250W compaq psu, from an unknown date, which is for sure not the original. I could buy another 250W ATX supply to see if that makes a difference. I used to have many PSUs laying around but the years go by and the collection shrinks.

starbond6 wrote on 2022-05-06, 00:40:

the years go by and the collection shrinks.

It does? Your collection and my collection should have a baby that may grow up to be a well adjusted collection.

All above is mere speculation. It might be much simpler. Certainly give it some time before acquiring clutter!