PCI Express to usher in PC changes

A new technology for connecting PCs to peripherals and other computers will bear fruit in 2004, but it won't conquer the industry overnight.

Michael Kanellos Staff Writer, CNET News.com
Michael Kanellos is editor at large at CNET News.com, where he covers hardware, research and development, start-ups and the tech industry overseas.
Michael Kanellos
5 min read

Intel is among the strongest backers of PCI Express, a successor to the PCI standard used to connect devices such as network adapters, chips and sound cards to one another inside PCs. Chips for building PCI Express into computers will begin to come out at the end of the year, with complete PCs arriving in 2004.

The technology will greatly alleviate one of the oldest bottlenecks inside today's PCs. Currently, links based on PCI-X, the latest take on PCI technology, run at 133MHz in most computers. PCI Express will run at 2.5GHz and transfer far more data per second than the existing standards, according to the PCI-SIG, a neutral consortium sponsored by computing companies. Eventually, PCI Express could hit 40GHz.

Additionally, PCI Express will simplify computer design. Many of these interconnections require data to travel in a parallel fashion, which requires that the wires connecting chips to each other be the same length. This has caused an explosion of serpentine wires on motherboards.

PCI Express is a serial link, which doesn't require parallel delivery, and can send more data down fewer wires. A board with six parallel PCI slots will come with more than 1,000 pins, metallic knobs that connect chips to wires. A similar PCI Express board can be made with fewer than 400 pins, said Mike Fister, senior vice president of Intel's Enterprise Platforms Group, who demonstrated PCI Express on stage last week for the first time at the Intel Developer Forum in San Jose.

"It will help us reduce the board area by 50 percent," Fister said. "It is a foundation technology that will drive the industry."

Although the Santa Clara, Calif.-based chipmaker has rounded up substantial industry support for PCI Express, it now faces the often slow task of getting equipment manufacturers to build with it and customers to buy it. Corporate buyers are notoriously cautious when it comes to embracing technology changes or new standards, especially when the changes affect expensive equipment such as storage systems and servers.

"The server environments are more conservative," said Kimball Brown, vice president of business development at ServerWorks, a leading producer of chipsets. "Inevitably, things probably do go serial, but we think it's not till the next revision...Generation two in the 2005 or 2006 time frame probably makes sense."

Long, winding road
PCI Express emerged from the skirmishes over interconnect standards in the late 1990s. In 1998, IBM, Hewlett-Packard and Compaq Computer formed a consortium to create PCI-X because of their collective frustration over the slow pace of PCI development.

Months later, Intel came out with an interconnect standard called NGIO, or next-generation input-output, as a potential successor to PCI-X. The major server companies then developed Future I/O. Eventually, Future I/O and NGIO were merged into InfiniBand. Intel then developed 3GIO, or third-generation input/output, in 2001. Also known as Arapahoe, the technology was adopted by the PCI SIG in August 2001.

In the end, the momentum to transform InfiniBand into a PCI replacement stalled, equipment makers adopted PCI-X, and PCI Express became the anointed successor. Advanced Micro Devices and some others, though, are adopting HyperTransport for similar functions.

PCI Express will change the innards of desktops, according to Pete MacWilliams, an Intel fellow. It will start to replace the current PCI bus inside PCs, which connects the processor to peripherals such as printers, as well as the AGP bus, which connects the processor to the graphics chip.

A variant of PCI Express will also eventually replace the "southbridge" in PC chipsets, a companion chip that connects the processor to the outside world. It will not, however, be used to replace the "northbridge," which connects the processor to main memory. The chipset consists of the northbridge and the southbridge.

"It is going to be a really big deal," MacWilliams said.

To show PCI Express' benefits, Intel has developed a concept PC called Powersville that uses a processor called Tejas. Intel will begin to deliver PCI Express chips in the second half of this year to manufacturers, and computers based on the Powersville design are expected next year. Intel also is delivering toolkits to software and hardware developers to ensure that future products will be PCI Express compatible.

Texas Instruments and other companies are equally enthusiastic and will be releasing PCI Express components next year or late this year.

Beyond the basics
While the PCI-SIG has signed off on the basic standard, more work is afoot. The group has finished a specification for add-in cards based on PCI Express, said Tony Pierce, PCI-SIG chairman and a Microsoft employee. This will be used to design plug-in cards for high-speed networks or IEEE 1394 "Firewire" connections.

And PCI Express researchers are working on a version that would allow signals to be transferred across a cable, making it possible to physically separate parts such as the processor and memory from network and storage subsystems.

Networking companies will begin to adopt PCI Express as well. For example, AdvancedTCA, a standardized blueprint for building networking equipment, relies on the standard. So far, 28 companies have announced plans to introduce 70 AdvancedTCA products in 2003, according to Udayan Mukherjee, technology architect and ATCA initiative manager at Intel, which is also driving the TCA standard.

But in the server market, competitor PCI-X looks likely to prevail in the nearer term.

Currently, Dell Computer, a close Intel ally, appears to be the strongest server backer of PCI Express, according to Insight64 analyst Nathan Brookwood. "Sun, IBM, and HP seem very committed to PCI-X. Dell's been lined up with Intel on PCI Express," he said.

The trouble for server companies could come if they pick a technology, like InfiniBand, that doesn't develop according to plan. It's the kind of bet that must be made years in advance while next-generation products are in the design stage, and making the wrong choice means losing market share, Brookwood said. The current economic climate also reduces any urgency to switch.

Back when 3GIO was first making its way into the industry, Intel said it would arrive in computers in 2003, but ServerWorks took a more cautious approach, predicting correctly that timetable was a year too fast.

Intel is more active than ServerWorks in driving technology change, Illuminata analyst Gordon Haff said.

"ServerWorks tends to take the attitude that once it's been proven that there's a market for a technology, (they'll) integrate it," he said. "Intel is much more likely to take the lead in throwing or forcing new technologies out there, evangelizing them and integrating them into (their) products, then backing away if it turns out people don't want them."