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With a parsimonious 133 megabytes per second of shared bandwidth, PCI has definitely become the short bus of PC expansion standards. Nearly every other port, slot, and link inside a modern computer is faster than the bus shared by a collection of 16-bit, 33MHz PCI expansion slots and a couple of on-board devices on the typical PC motherboard. A single Serial ATA connection can burst up to 150MB/s, saturating an otherwise-empty PCI bus.
Fortunately, help arrived recently for Pentium 4 motherboards with the introduction of Intel's 915 and 925X chipsets. These chipsets replace the tired PCI bus with the much faster, more modern PCI Express standard. Shared PCI slots give way to PCI Express X1 slots, which offer 250MB/s of dedicated bandwidth in each direction, or 500MB/s total, to a single device. PCI Express also replaces the PCI-derived AGP standard with a new PCI Express X16 slot that offers up to 8GB/s of total bandwidth, or nearly four times the bandwidth AGP 8X.
All of this is well and good, but there's been a catch. You see, the Athlon 64 has been hammering the Pentium 4 in many types of performance benchmarks, particularly the gaming ones, for nearly a year now. What's more, the latest versions of the Pentium 4 pull lots of power and generate lots of heat, making them not the most attractive CPU option. Right now, anyone buying a new system would have to choose between an Athlon 64 with AGP/PCI slots and a Pentium 4 system with PCI Express. That situation is about to be corrected, because chipset manufacturers are prepping core logic chipsets for the Athlon 64 with support for PCI Express. Our friends at Tech Report have prepared an on-hands preview of a sample motherboard based around VIA's K8T890 chipset.