With RDRAM (Rambus Dynamic RAM) now firmly established as a niche memory product, DDR SDRAM (Double Data Rate Synchronous DRAM) is set to become the most commonly used PC memory this year, with shipments of DDR chips soon to exceed those of low-end SDRAM chips. But users should be cautious when purchasing faster DDR333 memory as not all chips conform with standards defined by an industry group.
Executives from three of the world's largest memory-chip makers, Samsung Electronics Co. Ltd., Micron Technology Inc. and Hynix Semiconductor Inc., speaking at the Via DDR333 Summit here all expect DDR to dominate memory-chip shipments in the coming year, with DDR333 chips predicted to represent the bulk of shipments in 2003.
"In 2002, we are predicting almost 50 percent of our yields will be DDR333," said Mian Quddus, director of technology enabling at Samsung Semiconductor Inc. "If you go on to 2003, our yields are almost 80 percent to DDR333 and better."
Currently, most DDR memory chips are based on the DDR266 standard defined by the JEDEC Solid State Technology Association. DDR266, which uses a 133MHz bus that connects a PC's main memory with the chipset, offers maximum throughput of 2.1G bytes per second. By comparison, DDR333 uses a 167MHz memory bus that offers a 29-percent increase in throughput to 2.7G bytes per second.
"We feel strongly that DDR333 is an immediate transition for the industry, that our progression to DDR333 is unavoidable," said Brent McComas, founder and principal analyst at InQuest Market Research.
The boost in throughput offered by DDR333 doesn't necessarily mean users will see a corresponding increase in overall PC performance. Despite the increase in maximum throughput between the chipset and main memory and the faster memory bus offered by DDR333 memory, the effect on overall system performance is generally considered negligible because other important PC sub-systems, such as the front-side bus which connects the chipset with the processor, are not affected.
Users in search of even a modest performance gain should be cautious when purchasing DDR333 memory. Most early DDR333 chips are actually DDR266 chips that have been overclocked and are not as reliable as true DDR333 chips, said Desi Rhoden, president and CEO of memory industry group Advanced Memory International Inc. Users should make sure that the chips they buy are compliant with the JEDEC standard for DDR333, he said.
"Be careful because most of the very first DDR333 systems were essentially nothing more than overclocked (DDR266)," Rhoden said.
Unfortunately, checking compliance is easier said than done. One way is to check with the memory maker to confirm that part numbers on a stick of DDR333 memory match those of parts that meet the JEDEC specification.
The shift to DDR333 in 2003 won't last long. By 2004, memory makers expect to begin shipping second-generation DDR memory chips, commonly known as DDR-II, in volume.
Among the first DDR-II chips to go mainstream will be those based on the DDR-II-533 standard, which uses a 267MHz memory bus and offers throughput up to 4.3G bytes per second. DDR-II-533 prototypes are expected to enter production during the second quarter of 2002, said Quddus, adding that DDR-II-533 chips that are compliant with JEDEC standards will enter production during the first quarter of 2003.