At the high level, the PCI Express System is comprised of a root complex, which would be placed either in the chipset's North Bridge or South Bridge, switches, and finally end-point devices. The new item in the PCI Express topology is the switch. It replaces the multi-drop bus and is used to provide fan-out for the I/O bus. The switch provides peer-to-peer communication between different end-point devices and does not require traffic to be forwarded to the host bridge if it does not involve cache-coherent memory transfers.

System Topology using the new Switch

The following diagrams show possible PCI Express implementations across an entire range of platforms: Desktops and Mobiles, Servers and Workstations, and Networking Communications Systems.

PCI Express based desktop and mobile system

Server and Workstation system

Networking Communications system

An overview of PCI Express PCI Express Architecture
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  • Anonymous User - Saturday, September 20, 2003 - link

    The demo board is a BTX - ATX's successor:
  • Anonymous User - Thursday, September 18, 2003 - link

    First, for AGP, the official document about PCI-Express states that it can coexist with AGP. You must know that the PCI Express will only replace the PCI standard, so we can presume that the first board shipping with PCI Express will also ship with AGP.

    The PCI Express should not require any changes on power supplies, since it can go to lower voltages. I haven't read any technical spec, but it seems to be using some voltage-selection mechanism very similar to what is being used in USB devices (which did not require any power-supply mods).

    Finally, for the form factor... well, I admit that I dunno. Form what I have read, no form factor mod should be necessary, but the demo board confuses me!

  • Anonymous User - Thursday, September 18, 2003 - link

    the transition from PCI to PCI Express won't happen overnight. ISA slots had stuck around for nearly 10 years before they were finally gone, so don't assume that your PCI peripherals are obsolete just yet.

    Thats very nice. But how about my brand new fancy AGP graphics card? I assume that purchasing a PCI-express motherboard also forces me to buy a new videocard.

    Also when looking at the Intel layout demoboard I assume that there will also be a change in form factors and possibly also in power supplies. This means that all current cases would be obsolete then...

    I realy enjoy the things that are going to happen in 2004 to the PC marked though! It's a real revolution again.

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