Intel said the problem could cause systems to behave unpredictably or shut down, but added that it was confined to a subset of Intel's McKinley Itanium 2 processors.
The chip maker is working with server suppliers to fix the bug, but until a fix is available, Intel said customers could work around the problem by reducing the clock speed of their 900MHz or 1GHz Itanium 2 processors to 800MHz.
Intel has urged users to contact their system supplier to determine the best course of action. It will swap older McKinley processors for new ones upon request, but is not issuing a recall.
IBM has a handful of customers using the x450, but so far has not received notice of any problems with those systems, a representative said. The company was unsure when it would resume shipments.
Hewlett-Packard, Intel's main partner with the Itanium processor, is still shipping its Itanium systems. HP co-developed the processor with Intel, and has introduced the largest number of servers based on the chip.
HP was still working with Intel on the problem, and has not determined exactly what would be the best solution for its customers.
Unisys said it was satisfied with the measures Intel has prescribed, and there has been no impact on its shipment schedules.
To crash the system, a particular sequence of operations and events need to happen, according to Intel, which confirmed the problem in lab testing after a system supplier reported it earlier this year.
This indicated that it was not a problem with the core logic, said Nathan Brookwood, principal analyst with Insight 64.
Since all the chips have, essentially, the same logic design, a problem with only a particular set of chips indicates the problem is in how the electrons travel across the chip, he added.
Details as to what types of data or configurations cause a system to shut down are unclear. The problem is not related to a particular batch of processors, or any one instruction or data stream.
A field test can determine if a particular McKinley processor is affected by the bug, but problems can occur on systems that test clean in the field. Intel has developed a manufacturing test for processors coming out of its fabrication plants that identifies the problem.
Intel has not found any commercially available software that can cause the problem, said Kevin Krewell, senior editor of the Microprocessor Report.
System owners are likely to upgrade to a new processor, especially if Intel made the new Madison processor available as part of the deal, both analysts said. Madison is set for release in the middle of the year and features a larger cache than the McKinley processor.
Customers might opt to reduce the clock speed of their processors if they are using McKinley in a software development machine or on some mission-critical applications, Krewell added.
System managers can be conservative when it comes to critical applications, and sometimes it is better to take a slight performance hit than to risk having that system become unstable on a new processor, he said.
"There is no such thing as the perfect microprocessor. Intel handles these sorts of situations at least as well as anybody else in the industry," Brookwood said.