Does 133 MHz Processor Bus Clock Require DDR-Memory?
We recently published a comparison between the first two DDR chipsets, the ALi MaGiK-1, the AMD760 and the VIA Apollo KT133/KT133A (SDRAM). You will get better performance with the Apollo KT133A-chipset and a 133 MHz FSB CPU, than with VIA's Apollo KT133 at 100 MHz processor bus clock, but the gain is not quite enough to close the gap to 133 MHz FSB systems with DDR-memory. However, the only expense is a motherboard with the Apollo KT133A chipset. You can keep the PC133 SDRAM and don't have to invest in new DDR-memory. The Athlon/Duron processor can be kept as well, because you only need to lower the clock-multiplier with the well-known L1-bridge technique to reach the same or a slightly higher processor clock as before.
Right now DDR-DIMMs are still very hard to get and more expensive than standard PC133 SDRAM. Surprisingly enough DDR memory chips are hardly more difficult to produce than Single Data Rate chips. At the end of the manufacturing process, the bonding decides whether the chip becomes a SDR or a DDR model. Due to unavailability of motherboards, the demand for DDR memory modules is currently rather small. As soon as the memory makers will change their production in favor of DDR chips, we can expect falling prices.
As soon as motherboards with DDR-memory support become widely available, the most power-hungry Athlon-users might want to choose AMD760-platforms and DDR-SDRAM, because it offers the highest performance for Athlon processors to date. People who can live without the little performance gain achieved by DDR-platforms will be just as satisfied with Athlons at 133 (266) MHz FSB clock and PC133 SDRAM, as now offered by platforms based on VIA's Apollo KT133A chipset. Once DDR-memory has reached the same price point as PC133 SDRAM the story changes and DDR-platforms will become the smartest choice.