The overview in the PC
For a better overview, I have transferred the diagrams on the last page into a kind of flow chart that schematically shows the PC. We can see that the three large 12V main rails all have very different supply and return flows. As a user, you should definitely be aware of this if seemingly inexplicable things occur, such as chirping in the audio branch or the USB signal quality is affected. Sometimes all it takes is to plug a device into a different USB port. This has all happened before and this is exactly where we find the possible reasons.
Summary
The things that can very often be heard disturbingly in onboard sound and that can even have a negative influence on internal or external sound cards have most of their causes in the topology of the ground flows. I will discuss this again in a follow-up, where it is possible to isolate the internal sound card from these interfering noises with a single movement and how you can also manage to acoustically pacify external DACs or clean USB signals from these effects. This would go beyond the scope of today’s article, but it builds on exactly what we have seen today. The internal sound card could not be suppressed by any shielding, no matter how elaborate, but it could be electrically isolated from the housing. That’s a spoiler for now.
But you also have to consider the overall PC as a work of art. If you have two EPS connections on the mainboard and operate a powerful graphics card, you are always well advised to connect both EPS connections of the CPU to the power supply with good cables, even if the CPU does not require this in terms of performance. Furthermore, cable extensions on the 24-pin for modding purposes should of course also be planned with a certain amount of caution. We know that electricity always takes the shortest route. And if you’re not careful, it can even reach the PC case right up to the power supply housing and the four rear screws. With a bit of bad luck, the PC may even become an acoustic broadcasting center against your will.
At the end of the day, I’m still amazed that no one has ever discussed this further and that everyone has just resigned themselves to the charred 12-volt pins in the 12V2x6 connector without ever investigating the causes of the untouched ground pins. Or that one wonders where the onboard sound noise comes from and disturbed peripherals up to mouse or keyboard latencies. Ground loops are always a possible cause and it is advisable to look for them when errors occur. For this reason, motherboard spacers made of nylon are also rather counterproductive, as the tray is actually a nice collection ground. Unless the case surfaces are all so thickly powder-coated that there are no proper paths to the power supply unit. In the past, some power supplies even had separate earthing screws, but it’s a shame that this no longer exists. The hi-fi sector still has them.
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