Not to be confused with PCI-X
PCI has already been superseded for some time in professional servers where the need arose earlier and return on investment was most immediate. The solution was a version of PCI using a 64-bit slot that’s otherwise the same as PCI, and there’s also PCI-X – not to be confused with PCI Express.Although the interface for PCI-X is also 64-bit, rather than 32-bit, it operates at a higher frequency. The current version of PCI-X supports slots running at 66MHz, 100MHz or 133MHz - so bandwidth ranges from 533MByte/sec to 1,066MByte/sec.
Most PCI-X equipped motherboards will only have one or two slots running at the top frequencies, perhaps paired with a couple that are lower-rated. Know, too, that most PCI-X slots also support standard PCI cards, and many PCI-X cards will also work in standard PCI slots.
The added expense of supporting the PCI-X interface means that only adapters that need the bandwidth are offered as PCI-X. This includes Gigabit and 10 Gigabit Ethernet controllers, plus SCSI and other high-performance storage adapters, notably multi-port Sata.
In addition, some HDV-editing cards are available in PCI-X, the most talked about being the card that comes with Canopus's Edius NX for HDV combined hardware/software package.
Despite the arrival of PCI Express, PCI-X is continuing to develop. Version 2.0 is already set, offering further increased frequencies up to 533MHz using clock doubling or quadrupling. This will boost throughput to nearly 4.3GByte/sec.
PCI-X is now firmly entrenched in the enterprise market, and will remain so. But, it’s expensive to implement, and the connector is bulky - areas where PCI Express scores.
