On-board sound thru PCI-bus?

[Grakatt]

Is the on-board sound of todays motherboards run through the pci-bus?
Are built-in network cards, controller cards, soundcards somewhat of 'virtual PCI-units' ?

 

[Jeff7]

According to the block diagram in the manual for my 8RDA+ (nForce2 chipset), there appears to be an exclusive link to the 6 PCI slots from the southbridge - IDE, USB, sound all have their own separate paths. At least, that's what I interpret there.
I don't know about other boards though. Intel boards likely use a rather different design.

 

[Sunny129]

it depends on the particular mobo manufacturer, and when i say this i mean that if audio isn't integrated into the chipset itself, it is up to the manufacturer to add onboard audio in the form of a chip. and i really don't know what other bus they would run it on other than the PCI bus. go to the chipset link at the anandtech homepage. there you will find chipset introduction and architecture articles on just about every mainstream chipset released in the past couple years. for instance the chipset diagrams of the Intel 865 series show the south bridge to have 6-channel audio support. however i have an 865 board (abit IS7) and it uses a realtek chip for onboard audio. so i am assuming that, since abit chose to use the realtek chip for onboard audio (and not the ICH5R south bridge), the realtek chip is running on the PCI bus???

 

[Peter]

Both are possible, and actually done. It's easy to tell apart. If there's just a codec chip (Realtek ALC series, VIA 16xx series, C-Media 9xxx series etc.), then sound is generated by the chipset's own sound engine and passed to the codec via a dedicated AC97 bus link, not on the PCI bus. If there's a standalone PCI sound chip (C-Media 8xxx, VIA Envy24, or whatever), then it's obviously on the PCI bus.