It’s pretty clear to me that given the vast number of PCI Express plug-in cards available on the market today PCI Express has won the high-bandwidth, serial interconnect wars of just a few years ago.  No doubt, there are specific application niches were InfiniBand, RapidIO or HyperTransport work the best.

However, given the ever-expanding volume and types of PCI Express COTS boards available, you have to admit that PCI Express is the clear victor.  Maybe you disagree, but next time you’re searching for a plug-in board let me know how many non-PCI Express high-bandwidth, serial interconnect boards you manage to find.  I’m guessing that the number will be very small.

That brings us to a discussion on all the flavors of PCI Express that are now popping up. Does it matter that the interface is PCI Express version 1.1, 2.0, 2.1 or even the latest and greatest 3.0?  From the, “Will the cards work?” standpoint the answer is “Yes”, because the basic interconnect functionality is not affected by the PCIe version.

The PCI-SIG (Peripheral Component Interconnect Special Interest Group) did a very smart thing when PCI Express 1.1 was first developed as they built the basic PCIe interconnect in such a manner as to ensure scalability and backwards compatibility.  This critical specification feature enables the computer hardware to operate fine with just about any PCI Express card regardless of the board’s interface version.  So, if that’s the case why do I care about the various types of PCI Express interfaces?

Increased system performance is the primary reason you should care about the specific PCI Express interface.  A PCI Express 2.0 COTS board installed in an industrial computer will send its data over to the system host board (SHB) twice as fast as older PCI Express 1.1 boards.  Of course, this assumes that the SHB has PCIe 2.0 interfaces.  The same scenario plays out in an embedded motherboard.  If the motherboard is equipped with PCIe 2.0 card slots then any PCIe 2.0 card placed into one of these slots will send its data to the CPUs twice as fast as in a PCIe 1.1 system.  This speed advantage is cumulative and can be critical in high-performance computing applications.

Here’s a table that summarizes the key parameters of the various PCI Express interfaces.

PCIe 2.1 uses many of the interface architecture improvements developed for PCIe 3.0, but communicates at the same interface speeds used in PCIe 2.0.  PCIe 3.0 achieves twice the communication speeds of PCIe 2.0 through various architecture and protocol management improvements.  PCIe 3.0 silicon will start becoming readily available in 2011.

Trenton’s currently available JXT6966 or JXTS6966 single board computers, NTM6900 or WTM7026 embedded motherboards and BPC7041 or BPC7009 PCI Express backplanes are perfect examples of PCI Express 2.0 embedded computing hardware that’s designed to address the demanding needs of Video Processing, Test & Measurement and Medical applications.

Trenton JXM7031 MicroATX Motherboard