Rambus at the root of Intel's memory troubles

Intel today said it has discovered problems with a chip called the memory translation hub, or MTH, inside several Pentium III-based PCs.

Intel's plan to fix its latest bug--which will involve swapping the motherboard and memory in affected computers--could cost the company hundreds of millions of dollars, according to analysts. That puts the MTH problem in roughly the same class as Intel's infamous 1994 Pentium "floating point bug," for which the company took a $475 million charge.

Technically, the flaw exists in a chip designed by Intel. So why is Rambus to blame? Intel made the chip for computer makers that wanted to adopt Intel's latest chipset, designed to speak Rambus' language, without using the more expensive form of high-speed memory.

"It's the curse of Rambus," said one source.

Today's reported flaw is not the first related to Rambus, the controversial, high-speed memory technology adopted by Intel to become the standard for desktop computers. Earlier manufacturing issues and bugs related to Rambus delayed PC releases last year. Rambus memory, moreover, remains in short supply and costs more than twice as much as ordinary memory.

The recall announced today specifically relates to Intel's 820 chipset. The 820 typically connects an Intel processor to Rambus memory chips. Because of high price and tight supplies of Rambus chips, the MTH was invented so computer makers could use standard memory in computers designed to accommodate the 820.

Morgan Stanley Dean Witter analyst Mark Edelstone said Intel's problem was its attempt to make one chipset talk to both types of memory--not a great idea in retrospect.

"What it clearly points out is (that) to build a solution that is trying to alter the signaling is not a great solution," he said.

Questions remain
Although the flaw revealed today should be easily cured by the application of several million dollars, it won't eliminate questions. Intel plans to use a similar but redesigned translation hub to connect its forthcoming integrated processor, code-named Timna, to memory chips. Intel originally planned to use only Rambus-based memory for Timna, but it concluded Rambus chips would be too expensive and scarce when the low-end processor debuts later this year.

Along with a built-in graphics chip, Timna contains a Rambus memory controller; so to connect to standard memory, Intel must use another MTH.

"The Timna processor will use a new version of the MTH that will provide a great level of noise immunity," said Intel spokesman Michael Sullivan. In other words, the company will test, and retest, the Timna MTH before its release.

Rambus executives were not available for comment.

Dean McCarron, principal at Mercury Research, estimated that nearly a million PCs contain the faulty MTH combined with standard memory. PCs that contain Rambus memory or any other chipsets are unaffected.

In a worse case scenario, replacing the motherboards in all these systems would cost around $100 million. Replacing the memory, however, escalates the price, because Rambus chips cost more than double standard memory. Analysts said a typical system with 128MB of memory would cost several hundred dollars to upgrade to Rambus memory.

Customer requests could also be relatively high, since the motherboard replacement will allow customers to simultaneously upgrade their PCs.

"You bought a rather crippled (Pentium III) system, and Intel rewarded you for your mistake by giving you this faster memory," said industry analyst Bert McComas, founder of InQuest Market Research. McComas is critical of claims that Rambus memory is a big improvement, but he said that the MTH caused traditional memory to perform 5 percent to 15 percent slower in systems that use the translation hub.

Running out of options
While the memory swap is costly, Intel and the industry have maintained there wasn't another option. Currently, Intel does not have a replacement MTH or another chipset with a 133-MHz system bus, like the 820, that can "speak" to standard memory. The 815 chipset will contain both those features, but it isn't due to debut until later this quarter.

"If we had a different MTH today, we could do" a simple motherboard swap, Intel's Sullivan said.

Also unclear is whether there is enough Rambus-based memory in the works to satisfy Intel's replacement needs and the demands of the rest of the industry. Dataquest analyst Jim Handy said a lot depends on whether other memory makers have joined Samsung in shifting significant memory chip production to Rambus designs.

"The timing is right, provided guys like Hyundai, Micron (Technology) and NEC did a hard ramp after they were qualified" to make Rambus-based memory," Handy said. "All of these guys would have to have ramped pretty (hard) for this not to cause a big shortage. That could have happened."

Intel said it first learned of the problem last month from a computer maker that found a high number of system reboots and hang-ups with some motherboards using the 820, the MTH and synchronous DRAM. Around May 1, Intel said it noticed the bug could cause data corruption in some cases.

Then the company decided to offer replacement to all 820 users, although it stressed the problem shows up only on some boards and then intermittently.

The 820 chipset also has been a source of trouble for Intel. The introduction of the chipset was delayed last fall after the company discovered signaling problems between the chipset and Rambus-based memory. For that problem, Intel's solution was to reduce the number of memory slots from three to two, a change that required it to scrap more than 100,000 motherboards.