Intel has stopped shipping its top-end server chip because of a bug that could cause servers to crash. Intel began shipping the chip, the Pentium III Xeon with 2MB of high-speed "cache" memory, in March. But about a month later, a company that sells computers using the chip notified Intel that it found a problem while testing the chip, Intel spokesman Bill Kircos said on Tuesday. Intel was able to reproduce the problem but unable to patch existing systems, Kircos said. Accordingly, the company stopped shipping the chip in mid-April. Intel is changing the chip's manufacturing process, and a new version of the processor is expected to begin shipping in mid-August, Kircos said. Until then, Intel will swap out the defective chip with the slower 700MHz version. The problem is comparatively minor because few customers had the chip at this early stage in its life, Insight 64 analyst Nathan Brookwood said. "It's very contained. I doubt any end-users have experiences or are likely to experience this problem," Brookwood said. In addition, the customers buying the chip are comparatively rare and often are satisfied with a 700MHz chip. Though Intel characterised the problem as minor, the company doubtless would prefer to sell the 900MHz model, which sells for $3,692 (about £2,580) in quantities of 1,000, compared with $1,980 (about £1,390) for the 700MHz chip. It's not easy designing high-end chips, which typically feature more circuitry and run under higher stress than the CPUs of desktop computers. Sun Microsystems found a problem in its new top-end UltraSparc III chip that forced the company to disable a speed-boosting feature, even though the problem only was found in lab testing. But companies have to be conservative when dealing with demanding server customers, the people in charge of the computers that handle critical business operations such as tracking inventory or booking plane reservations. The Pentium III Xeon is one of a host of high-end server chips Intel is selling as a way to take on Sun and other more established server companies. The 900MHz Pentium III Xeon with 2MB of cache is the current top-end product for multiprocessor servers. Eventually replacing it will be a server version of the Pentium 4 chip, code-named Foster and sold since May under the name Xeon with no "Pentium" prefix. But the 2MB cache feature, which increases the size, speed and price of the chip, isn't yet available on the Xeon. That model is expected in the first quarter of 2002, Kircos said. Also coming in 2002 is a version of the Xeon chip built with smaller, faster 0.13-micron circuitry, Kircos said. This chip is code-named Prestonia, Brookwood said. But for the long term, Intel is banking heavily on a totally different design called Itanium. This chip, which began shipping in servers in June, speaks a totally different language from the Pentium and Xeon lines. Because it's such a dramatic departure and requires big changes to software, it is largely used as a development system at present. Intel had hoped to be able to screen for the problem so it could continue to sell 900MHz chips that didn't show the defect, Kircos said, but that plan didn't work out. "The workaround we hoped would keep them shipping was a screen," he said. "We didn't feel the screen met our quality standards. We decided to go with a manufacturing tweak." Intel's problem occurs in rare circumstances in "extreme" testing and hasn't been reported by any system users, Kircos said. When the problem occurs, the chip fails to write information to a part of the processor that keeps track of what tasks are going on, locking the chip into an endless loop of pointless processing. See Chips Central for the latest on processors and the semiconductor industry. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the Chips Central forum Let the editors know what you think in the Mailroom. And read other letters.