
344 5.2 System Optimization for Exchange 2003
PCI, PCI-X, and PCI Express Bus Considerations
Initially, PCI and PCI-X buses were implemented at either 66-MHz or 33-
MHz clock speed. On high-end and modern servers, we now see the gen-
eral availability of additional generations of PCI interfaces:
PCI-X bus that operates at 64-bit and 100- or 133-MHz clock rates;
PCI-X 2.0 bus that can operate at clock speeds of 266- and 533-
MHz and offer backward compatibility to legacy PCI adapters;
PCI-Express bus that offers scalability and performance for the
upcoming processor and systems architectures. PCI-Express (also
referred to as PCI-E) brings improved clock ...