View Full Version : GB Lan stress on PCI bus..?

06-12-2003, 09:26 AM
I've heard that integrated Gigabit Lan on a mobo can put so mutch stress on the pci slots so that the bus bandwith left is not enough for high performance soundcards like the Audigy2 for example.. Is this true or is it solved on those new 875P mobos..:?:


06-16-2003, 05:51 AM
I doubt it.

On gigabit ethernet, your hard drive becomes the bottleneck, and by the time Hard drives exceed 1 GBit read or write speed, all the quirks will have been worked out long in advance.

And sound cards use a NEGLIGABLE amount of internal bandwidth when compared with what a network card can use.

06-16-2003, 10:57 AM
It really depends on how the gigabit lan is intergrated. If it is integrated into the southbridge on it is a PCI card, u will only ever come to about a third of the Gigabit potential as the 133 Megabytes/second bandwidth of the southbridge is split between all PCI cards and various other functions. Note that the 133 magabytes is actually more like 1064 megabits as megabis anbd megabytes are different. This would suggest that the ATA100 capable drives are not infact the bottle neck, but the southbridge is.

However, if the gigabit lan is incorperated into the CSA of the northbridge, it is independant of the PCI bridge and is therefore not succeptable to its bandwidth limitations, thereby allowing the gigabit connection to actually come cloer to 800megabits instead of the lesser 300 that it would get from the PCI connection.
see this http://www.intel.com/design/chipsets/875P/pix/875_SMALL.gif.

If u look at the Communications Streaming Architecture of the intel 875p chipset, this is where the gigabit lan is incorporated, avoiding the PCI bus.

U can also see that the southbridge handles, with its bandwidth the onbaord audio, ATA100, SATA, PCI bus, USB, Bios and Raid channel. That is alot of stuff all trying to use the same highway.

Ther is a distinctionthat needs to be made. gigabit lan is equivalent to 1048 megabits or 131 megabytes. I think there is a common misconception that gig lan is gigabyte lan, not gigabit.

Hope u can make sense of all this.