Pentium Chip Replacement Offered by IBM : Computers: The action is seen as a brilliant public relations move. Intel defends its response to discovery of flaw.

Seizing a public relations opportunity at Intel Corp.’s expense, IBM Corp. on Wednesday offered to replace flawed Pentium microprocessors for customers who fear their computations might be at risk.

IBM’s offer--likely to prompt similar moves by other computer makers--follows several days of concern among advanced-computer users since the widespread disclosure last week of a bug in Intel’s popular Pentium computer chip. In rare instances, the glitch can produce errors in complex division problems.

With speculation swirling that Intel might launch a recall of Pentium chips, shares of the Santa Clara, Calif.-based company, the world’s leading manufacturer of chips, tumbled $2.375 on Wednesday to $63.125 in a late selloff on Nasdaq. The stock was the most active in U.S. composite trading, with 11.2 million shares changing hands.

But Intel spokesman Howard High denied that the company has plans for a recall, and he said its campaign to work with individual customers “seems to be going reasonably well.”

“We are still handling it on a case-by-case basis,” High said. Calls from concerned owners of Pentium machines, which have poured in by the thousands, peaked Tuesday, he added.

High said most customers are satisfied when Intel engineers explain that they are not likely to be affected. To date, the problem has manifested itself only in complex mathematical problems.

However, High said, in cases where customers do highly technical work or have an “emotional concern” that they might be plagued by the bug, Intel is working to arrange for replacements.

Over the weekend, Intel Chief Executive Andrew Grove issued a statement on the Internet, apologizing for any anxiety and defending Intel’s response.

Even so, many computer users contend that Intel has handled the problem badly. A high level of dismay greeted Intel’s revelation last week that it had known about the bug since June but had chosen not to announce it because it viewed as minute the chance that most users would encounter it. Intel began shipping corrected chips a couple of months ago.

Analysts viewed IBM’s decision to deal directly with its customers as a brilliant public relations stroke.

Jerry Banks, an analyst with Dataquest Inc., a San Jose high-tech research firm, said it allows the computer maker to grab back some control of the market that Intel has snared with its high-profile “Intel Inside” campaign.

“IBM is saying, ‘It’s my box, I’m the person making it and selling it, I’ll take care of you,’ ” Banks said.

The gesture is also fairly low-risk for IBM. Of the millions of IBM computer systems installed or in the pipeline, a small fraction are based on the Pentium. Moreover, Intel will furnish new, debugged Pentiums to IBM free of charge. Still being negotiated is which company will pay for the service call required to replace the part.

As part of its effort, IBM said it will establish special telephone lines to help customers determine whether they have a problem.