AGP Bandwidth on PCI Bus? Need help...

[AtomicDude512]

So does the AGP Bus really take some from the PCI Bus, like I have heard said? And if so, would less PCI devices mean better AGP performance? Thanks!

 

[Smilin]

Not quite sure what you're talking about. Maybe this will answer

The Northbridge chip of your chipset is connected to: CPU, Memory, AGP bus, the southbridge.

The Southbridge chip of your chipset is connected to: Drive controllers, PCI bus, the northbridge.

As you can see the AGP bus is in no way related to the PCI bus. Back when ISA was around it would hang from the PCI bus so it was sort of "shared" bandwidth. AGP was designed to be completely separate from these issues. If you want to see some proof of this just run winamp on a PC with a PCI video card. Scroll your mousewheel quickly and you'll hear static in your music...a result of the scrolling video data overloading the PCI bus which is trying to deliver data to the PCI sound card. Do this same thing with an AGP video card and you won't notice a thing.

Now your computer as a whole may slow down a bit while "operating" some extra PCI cards but you won't be able to tell with the naked eye.

hope this helps.

 

[everman]

I would really like to see a redesign of the AGP bus and slot in order to supply more power without using power cables like we do now and higher bus speeds. Also to better accomodate better cooling systems.

 

[CTho9305]

Originally posted by: everman
I would really like to see a redesign of the AGP bus and slot in order to supply more power without using power cables like we do now and higher bus speeds. Also to better accomodate better cooling systems.

It's called AGP Pro. The slot is slightly longer - I think all Asus motherboards have them. There are 55W and 110W versions IIRC.

 

[borealiss]

"So does the AGP Bus really take some from the PCI Bus, like I have heard said? And if so, would less PCI devices mean better AGP performance? Thanks! "

generally no. more agp traffic does induce more overhead in the northbridge though, and this can have an impact on pci performance indirectly depending on how well the northbridge handles heavy i/o on both buses simultaneously.

 

[AtomicDude512]

Originally posted by: borealiss
"So does the AGP Bus really take some from the PCI Bus, like I have heard said? And if so, would less PCI devices mean better AGP performance? Thanks! "

generally no. more agp traffic does induce more overhead in the northbridge though, and this can have an impact on pci performance indirectly depending on how well the northbridge handles heavy i/o on both buses simultaneously.

So if I disabled all the devices I dont use like Serial and parallel ports, onboard audio and game port and USB that would make for less I/O utilization on the Northbridge, freeing it to make my GeForce4 Ti 4200 faster?

 

[KilroySmith]

No. If you're not using the devices, they're not creating any I/O, thus not using any bandwidth.

/frank

 

[TerryMathews]

Originally posted by: AtomicDude512

Originally posted by: borealiss
"So does the AGP Bus really take some from the PCI Bus, like I have heard said? And if so, would less PCI devices mean better AGP performance? Thanks! "

generally no. more agp traffic does induce more overhead in the northbridge though, and this can have an impact on pci performance indirectly depending on how well the northbridge handles heavy i/o on both buses simultaneously.

So if I disabled all the devices I dont use like Serial and parallel ports, onboard audio and game port and USB that would make for less I/O utilization on the Northbridge, freeing it to make my GeForce4 Ti 4200 faster?

See, most devices on your PC (serial ports, parallel port, PCI cards) use IRQs to catch the CPUs attention. It's the equivelant of a "Hey look at me dummy" flag.

Believe you me, that Ti4200 uses more bandwidth than all the other devices on your PC combined. Stripping it to the bone won't make it go any faster. Unless you've got a 64 bit PCI/66 RAID card. And if you do, you should really know about this stuff. That would be like owning a NASCAR and not knowing how to drive a stick.