Asustek late last year Asustek pledged to release a high-performance motherboard based on four-channel PC1200 Rambus DRAM. It was to be based on a chip set from Silicon Integrated Systems Corp.

Now, SiS appears to have dropped support for Rambus, too. "The better timing was the end of last year, but we missed that window. Now everybody is talking about PCI Express," said Hank Lee, a chip set project manager at SiS.

In 2002, SiS released the R658, which was the first non-Intel chip set to support Rambus in the desktop PC segment, followed by the R659 late last year.

The R659 chip set never gained traction in the market, partly because of pricing and also because OEMs were already anticipating the switch to PCI Express for high-performance systems.

Asustek pulled back from the project because the performance of the chip set wasn't as "exciting as we expected," said a motherboard project manager, who asked not to be identified.

During the CeBIT trade fair this year, media reports said SiS might soon release follow-ups to the R659. But Rambus, which worked closely with SiS on the chip set, said it has not recently provided any direct design support.