A bug--or, in chipmaker parlance, errata--in the chipset for the Pentium 4 can degrade performance when video or other graphical data is processed through a PCI bus, an internal channel for data, Intel has stated. Because of the bug, consumers may experience slow processing if they connect a second monitor or an additional graphics card through one of the PCI expansion slots in a Pentium 4 computer.
The chipset bug was discovered before the release of the chip and prompted the company to delay the introduction of the Pentium 4 from Oct. 30 to Nov. 20 so it could study the extent and cause of the problem, sources said.
Although the bug has yet to be fixed, the limited circumstances in which it can cause problems did not justify further delays, said Howard High, an Intel spokesman.
Instead, the Santa Clara, Calif.-based chipmaker warned computer makers of the existence of the problem before the Pentium 4 launch and advised PC makers how to circumvent it. A version of the chipset that is not affected by the bug will also come out in the relatively near future.
Overall, the potential effects of the problem appear to be limited. Computer manufacturers such as Compaq Computer are warning of the problem on the product specification sections of their Web sites.
In addition, most companies have figured out ways to work around the problem and are configuring their computers to avoid conflicts. For instance, for customers interested in buying a Pentium 4 computer capable of running two independent monitors at once, Compaq and Dell Computer are offering the option of a Matrox G450 graphics board rather than the standard graphics subsystem.
The Matrox board channels both monitors through the Advanced Graphics Port (AGP), a faster data pipeline that is not affected by the bug. Most graphics boards can handle only one monitor at a time through the AGP. Pentium 4 computers contain only one AGP slot, but most have four to five PCI slots.
Because problems can be avoided through configuration, the bug is mostly a worry for consumers who buy Pentium 4 systems before a permanent fix but later upgrade their systems on their own by plugging graphics hardware into an open PCI slot.
Stock traders are one group that could be affected, as they are a prime audience for two-monitor computers. Often, traders use one screen to monitor data feeds and another to crunch numbers. Analysts, nonetheless, seemed unconcerned.
"This is an extremely minor bug," said Dean McCarron, principal analyst at Mercury Research. "Virtually all chipsets have errata."
Until a new version of the chipset comes out, Intel is advising PC makers to adapt to the problem by routing additional graphics data through the AGP bus or by not advertising dual-monitor capabilities, High said.