P4 Memory: New Options

Behind the Numbers

Industry analysts have long stated that the combination of P4 and RDRAM would offer the best performance because Intel and Rambus, RDRAM's creator, designed the technologies to complement each other. The P4's frontside bus supports transfers of up to 3.2GB per second, as does two-channel RDRAM. At best, DDR can support 2.1-GBps transfers; SDRAM offers a maximum rate of 1 GBps. So how did the DDR-based PC outrun the RDRAM unit?

Senior analyst Kevin Krewell of research firm MicroDesign Resources suggests RDRAM's large bandwidth may not offer much benefit with standard business applications--the ones most people use. RDRAM's bandwidth may come in handy for processing multimedia (such as video or music streaming), which uses large chunks of data, but it's not fully utilized in business apps, which use short bursts of data, he says. In tackling those short data bursts, RDRAM suffers from its biggest drawback, longer latency, which is the amount of time between when a CPU requests data from memory and when it actually arrives.

RDRAM's fast bus may simply be more than is necessary for most of today's applications, Krewell adds.

Top Value

Until more programs that need RDRAM arrive, DDR's shorter latency and lower cost make it a good option for performance-minded users. And Via's $1300 estimated price for our test PC makes the platform a bargain. Users unwilling to embrace Via to get a P4 DDR PC should have an Intel option in early 2002. (Intel has filed suit against Via to get the unlicensed chip set pulled off the market, which may give buyers pause. For its part, Via has filed patent suits against Intel relating to the P4 CPU.)

SDRAM P4 PCs should offer a decent balance of value and performance. Dell has aggressively priced its RDRAM-based 8100 at $2099, while the SDRAM-based 4300 should cost a somewhat high $2079. We expect most SDRAM PCs to offer larger savings over their RDRAM counterparts than the Dell units do. If you work often with bandwidth-intensive apps, your best bet may be an RDRAM-based system, despite its premium.