President's Corner:  PCI Express Isn't a Train!

      by Bill James, President OKCPCUG        July 2004

Keeping up with the latest computer technology can be likened to a fast-moving freight train – if you wait too long, you find that the train has left the station and you behind. Advances in technology used to be limited to computer chip manufacturers introducing a newer and faster processor every 6 or 8 months, but now other hardware is getting into the act to keep pace with the faster processors. New hardware is hitting the market at a rapid pace with the promise of making your computer faster and more efficient.

Changes to the desktop platform began with the use of Peripheral Component Interconnect (PCI) introduced several years ago. It was the first breakthrough to speed up communication between the processor and the motherboard, replacing the slower Industry Standard Architecture bus. The AT version was the de facto standard for IBM computers for many years to connect devices to your computer, but today almost all computers use PCI. The newest version of PCI is being launched as PCI Express. It will consists of a whole hosts of changes of what we know today as the AT bus.

PCI Express is the long-awaited serial interconnect standard. It will be capable of moving 8GB/sec of data bidirectionally (4GB per second in each direction, simultaneously). The single-lane connectors support an effective throughput of 2 gigabits per second in each direction (250 Mbytes/sec – almost twice PCI's maximum theoretical throughput of 133Mbytes/sec), but take up less space than the older PCI connectors did. We'll likely see motherboards with a couple of single lane connectors, a 16-lane graphics interconnect and several legacy PCI slots.

Computer memory is also about to get a boost. Intel is taking a leadership position in the area of DDR2 memory support. DDR2 will eventually supplant current generation DDR memory, though the current DDR will be around for some time to come. But why move to yet another memory standard?

As processor speeds increase, the bottleneck becomes memory. Whether you're talking about the high clock rates of the Pentium 4 processor or the integrated memory controller built into the Athlon 64, advances in CPUs are racing ahead of memory speeds once again. Overclocking aside, memory performance has been advancing at a slow, steady pace. The result is that memory performance hampers the overall throughput of today's systems.

Audio is not being left out; Intel is also introducing High-definition audio. Suffice it to say that this isn't the AC97 codec use in today’s computer that produces barely tolerable sound. This new standard will be capable of pushing eight 192 KHz, 24-bit audio streams, Intel's HD Audio is a key component to Intel's push into the living room. To that end, Intel is working with the folks that put logos on audio gear, like Dolby, DTS, and others to get properly certified.

Other news is that processor sockets are being revamped. The current Pentium 4 package has 478 pins, but the new format will have up to 775 pins. According to Intel, most of the additional pins are for power and ground.  The new socket has some advantages over the old socket format, but also requires some changes in the way you handle processors. For one thing, the pins are now in the socket, while the CPU underside has an array of flat contacts. This is essentially backwards from the way it's been. You drop the chip into the socket, and close a pressure cover that then latches down with a ZIF-style lever. The heat sink no longer requires a large amount of pressure to press down onto the surface of the CPU package.

These are just a few advances that we will be seeing in the next few months. New motherboards will be arriving to support this new technology. So if you are in the market for a new PC you may want do a little homework before you buy.

Bill James is President of the OKC PC Users Group. Bill can be reached at james@qns.com