During the past year, Intel has been claiming that the main bottleneck in the memory subsystem is insufficient bandwidth. Many experts have expressed their doubts about this, but the trade press seemed to have been convinced until recently. Tom’s Hardware Guide did a comparison of DRDRAM, PC100 and PC133 recently, which showed that DRDRAM is actually slower in most applications than PC133, and in some cases even slower than PC100.
The reason for this is that most applications are limited by the latency, not the bandwidth. By disabling the L2 cache, the results showed that more bandwidth memory bandwidth was beneficial – no big surprise. Even with this non-realistic situation, the benefit was less than 10% at best. On the other hand, the cost of DRDRAM has been estimated to be from 50% to 200% higher than PC133. The choice seems very obvious, and Intel has apparently finally agreed by including PC133 support in the Camino chipset.
VIA Technologies has been spearheading the PC133 effort since early this year. Their Apollo Pro133 chipset is already available, and even includes support for Virtual Channel SDRAM, which lowers the latency substantially. Despite Intels best effort to ‘encourage’ manufacturers to fully support DRDRAM, it is obvious that the industry has embraced PC133. For this reason, we believe that PC133 will be the memory standard for at least the next 6 months to 1 year, with DDR SDRAM (PC266) likely to be the successor. In this comparision we will look at what you can expect from PC133 memory today, and give our thoughts about the near term benefits.
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