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Maybe not every one of you is familiar with the term 'DDR333'. There have been too many different names for DDR-memory so far. The new double data rate memory supported by SiS645 is clocked at 333 MHz vs. the 266 MHz of the fastest DDR-DIMMs so far. DDR266 is also known as PC2100 memory, which comes from the fact that DDR-SDRAM provides a bandwidth of up to 2133 MB/s. DDR333 could therefore also be called PC2700, as its peak bandwidth is 2666 MB/s.
|Dual Channel PC800 RDRAM||PC2700 DDR-SDRAM (DDR333)||PC2100 DDR-SDRAM (DDR266)||PC1600 DDR-SDRAM (DDR200)||PC133 SDRAM||PC100 SDRAM|
|Clock||400 MHz||166 MHz||133 MHz||100 MHz||133 MHz||100 MHz|
|Differential?||Yes 2x||Yes 2x||Yes 2x||Yes 2x||No 1x||No 1x|
|Bus Width in Bit||2 x 16-bit = 32-bit||64-bit||64-bit||64-bit||64-bit||64-bit|
|Bus Width in Byte||2 x 2 Byte = 4 Byte||8 Byte||8 Byte||8 Byte||8 Byte||8 Byte|
|Peak Bandwidth||3200 MB/s||2666 MB/s||2133 MB/s||1600 MB/s||1066 MB/s||800 MB/s|
You can easily see that dual-channel RDRAM, as found in Intel's 850 Pentium 4 chipset, is still providing the highest bandwidth. However, DDR333 is pretty close and coming with 25% more bandwidth than DDR266/PC2100 DDR-SDRAM. All SDRAM types benefit from a lower latency than RDRAM, which can make up for lower bandwidth in the majority of today's applications.