Bandwidth… We all want it and we all need it, but can we get enough of it? Well, PCI Express is here to satisfy our appetites for the next several years. PCI (Peripheral Component Interconnect) was originally developed by Intel Corporation, but is now slowly coming to an end, but probably won’t be entirely discarded for a couple of years. Why do we need PCI Express you might ask? Well, the PCI 2.2 bus and other revisions just don’t provide us with enough bandwidth to support the evermore demanding peripheral cards. Hard drive controllers and networking cards just aren’t providing enough bandwidth that some hard drives have the potential to offer.

The reason is because PCI only offers a throughput (maximum theoretical bandwidth) of 1.056Gbps (gigabits per second) while Serial-ATA hard drives can offer a maximum of 1.5Gbps (3.0Gbps with SATA II); however, if a SATA controller can only have a transfer rate of 1.056Gbps, the SATA drive will have a transfer rate of only 132MBps (megabytes per second), which is roughly equivalent to ATA-133 technology. This is true if there are no other peripherals requesting use of the bandwidth. PCI shares that 132MBps bandwidth as it only uses one PCI bus which is connected in parallel. Although there are other PCI versions available, most motherboards and components use the 32-bit PCI which operates at 33MHz.

Now for all of you with the Gigabit LAN cards, just know that at one thousand megabits per second, you are using approximately 95% of your available PCI bus’ bandwidth. This leaves little room for any other peripherals to use bandwidth. Most of the time, however, you will only be using a sound card on the PCI bus, but if you have a few other bandwidth-demanding components, you will have performance loss somewhere in the PCI bus, and that may likely sacrifice data transfer rates with your LAN. While most of us actually may find PCI to be satisfying currently, we are rapidly approaching the point where PCI just won’t be enough for our needs. Thus, enter PCI-Express…

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