Is Rambus Worth the Price Yet?

The Pros and Cons of Rambus

The biggest strength of Rambus is its high throughput, which lets it pump three times more data per second than PC100 SDRAM. Its alleged weakness is something called latency. This boils down to delays between the time data is requested from memory and when it's delivered to the CPU. Current CPUs, software, and tests tend to exacerbate its shortcomings and work against its strengths, according to memory technology experts.

A shaky consensus says RDRAM's latency is longer than SDRAM's, especially the PC100 variety (but even this is hotly debated). In programs like word processors and certain databases, which tend to jump around a lot making small data requests from memory, a longer latency hampers performance. It's less of a problem when you're watching DVD movies or editing video, where megabytes of data get blasted out, then stop for a while. RDRAM's greater throughput also comes into play with these types of apps.

However, even today's chart-topping 1-GHz CPUs can't begin to push its limits. "The benefit [of Rambus] compared with the pricing is out of line," concludes Nathan Brookwood, senior analyst at Insight 64.

RDRAM typically adds around $200 to $400 to the cost of a preconfigured PC--not an absurd premium, but disproportionate to its piddling speed increase. On upgrade chips, price differences really get outrageous. One May posting at Kingston Technology's ValueRAM.com site listed 128MB of the cheapest, slowest type of RDRAM for $370 more than the fastest non-DDR SDRAM; 256MB RDRAM modules cost more than $1000, versus PC133 SDRAM's $350. As memory vendors learn to make RDRAMs more cheaply, prices should drop.

"A year from now, I think a price premium for Rambus in the range of 25 percent compared to SDRAM is very achievable," predicts Avo Kanadjian, vice president of worldwide marketing at Rambus.

DDR's Contribution

Intel archrival Advanced Micro Devices favors DDR over RDRAM. Its price premium is certainly better--about 8 to 10 percent for now, and expected to drop to about 5 percent when volume production begins, according to a Semico Research analyst.

DDR should also have less of a problem with latency than RDRAM. But although DDR's maximum throughput is twice that of current SDRAM and competitive with that of RDRAM, it won't approach that of a soon-to-be-released dual-channel version of RDRAM. There is also some concern about motherboard design issues related to DDR's wide data bus.

Bob Eminian, vice president of marketing at Samsung Semiconductor, a manufacturer of all four memory types and the highest-volume RDRAM vendor, dismisses talk of DDR's problems, saying hardware designers have been working out any technical issues for more than two years.

"We're forecasting that by the end of next year, Rambus and DDR will hold about the same market share," Eminian says. (The forecast doesn't include DDR SDRAM in graphics boards.) Expect to see AMD Athlon PCs with DDR later this year; the memory standard is already appearing in high-end servers.