The Answer To Bandwidth Questions: DDR333
PC2700 DDR-DIMM from Corsair Microsystems. Such memory was specifically designed to run clock speeds of 166 MHz.
Even though the ATA/133 interface, USB 2.0 and AGP 8x are very important as well as desirable features, they each have less influence on overall performance than the memory controller plus the memory combined. With the clock speed increased from 133 to 166 MHz (double-pumped), the maximum bandwidth of DDR-SDRAM climbed from 2.1 GB/s to 2.7 GB/s (which is why the standards are also called PC2100 and PC2700).
This is still lower than the bandwidth of dual-channel RDRAM (3.2 GB/s), but conventional SDRAM can live with only a fraction of the latencies of RDRAM, thus resulting in equal or better performance (see reviews of SiS645 , SiS645DX , VIA P4X266A ).
This is also the main reason why the memory clock of RDRAM was increased from 400 to 533 MHz as well (PC1066 RDRAM). Read our recent review of the 850E chipset and the Pentium 4 at 2533 MHz for details. By the way, the test setup that we used there is the same one that we used to review the new VIA chipset. More details later.
When talking about DDR333 memory, we should not forget that there are two types of RAM available : CL 2.0 and CL 2.5 modules. Only a few days ago we published an article showing the difference between fast (CL2) and slow (CL 2.5) memory setups. Basically, shorter latencies and thus CL2 memory should always be preferred.
Many THG readers have been asking about the performance difference between DDR266 at CL2 and DDR333 at CL2.5. Well, the difference is quite significant, or in other words : DDR333 is always faster than DDR266, no matter which timings you are running. Still, we recommend that you go for the faster DIMMs if possible.
P4X333 : Chipset Details