Caminogate failure finally explained

World learns why Rambus boards only have two slots

San Jose At last the truth can be told.

Samsung's Yong Joo Han, boss of RDRAM planning, said the Intel recall of its Vancouver mobos last year was caused by the RIMM connectors themselves.

Fans of the Caminogate saga will remember that before the SDRAM Cape Cod got the chop, the VC820 Vancouver (the board that Cape Cod users get in exchange for their dodgy mobos) was itself involved in an embarrassing recall of its own when it was discovered that it didn't work when all three of its RIMM slots were populated.

After the recall, the VC820 re-emerged as a two slot board, and ever since, all 820 Rambus mobos have had a two-slot limit.

Earlier in the day at the Platform conference in San Jose, Micron's Justin Sykes was describing to us how to build a DDR mobo (don't try it at home, was the message), and stressed the importance of keeping a careful eye on impedances between the chipset and the memory.

When we asked Samsung if they could explain the reason for the limit of two RIMMs per mobo, impedances came up again - it transpires that the downfall of the original Vancouver was the increased impedence inherent in having three sets of connectors.

With or without gold plating, three into Rambus just doesn't go.

"So that's it for single channel Rambus with more than two RIMMs?" we asked.

"Not necessarily..." replied Yong Joo Han, enigmatically.

So watch out for Son of Rambus, coming to a mobo near you soon(ish). ®