|
What is PCI Express?
PCI Express is a serial-based technology, where data can be sent over the bus in 2 different directions at once. Each 1x lane in PCI Express can transmit in both directions at once. PCI Express bandwidth, however, is not shared the same way as in PCI, so there is less congestion on the bus.
How does this affect you?
PC manufacturers continue to decrease the number of PCI slots, as they transition from legacy PCI to PCI Express. If you recently purchased a new PC, you may have noticed the traditional PCI board does not fit in the new PCI Express expansion slots.
But the size isn't the only thing that's changed. If you use a PCI board, you've been utilizing a parallel bus system on the motherboard. PCI Express employs a serial-based technology, similar to USB.
In addition to the bus technology upgrades, such as faster speeds and deeper FIFO rates, the PCI Express board touts many advantages over the traditional PCI card including point-to-point link dedicated to each device, instead of PCI shared bus; lower latency in server architectures due to a more direct connection to the chip set; smaller form factor with easier implementation for system designers and advanced features via isochronous channels for guaranteed bandwidth delivery, advanced power management and hot swap support.
Increased bus bandwidth = increased overall system performance
PCI Express addresses slow transfer speed by making it much faster and easier for data to transfer in the system. For example, Quatech's 1x cards are at least 118% faster than legacy PCI boards.
|
|
PCI vs PCI Express
|
The difference lies within the boards... |
|
Figure 1a - PCI Serial Board
One visual difference between the two, is the size of the gold fingers, or edge connectors. In Figure 1a, the DSC-100 has larger gold fingers. |
 |
Figure 1b - PCI Express Serial Board
The PCI Express serial board has smaller gold fingers. If you would use a PCI Express slot, the DS-PCIE-100 model is compatible to the DSC-100. |
PCI Express uses a point-to-point connection, connecting only 2 devices and no other devices can share this connection. Where, as with a PCI board, all PCI slots are connected to the PCI bus and share the same data path. As with PCI Express slots, each PCIe slot is connected to the motherboard chipset using a dedicated lane and not sharing this lane with other PCI Express slots.
Although PCI and UPCI Cards can be used in a variety of platforms, PCI Express reflects an industry trend to replace legacy shared parallel buses with high-speed serial buses. They both have the same dimensions and are equipped with rear brackets, the difference lies in the I/O connectors. PCI Express has 36 pins versus the 120 pins on a standard PCI connector.
|
|