24. DDR2 Memory In Dual-channel Mode Does (hardly) Anything In Practice

As the benchmark results tables reveal, the speed advantage afforded by the new platform's dual-channel DDR2-533 memory is a maximum of 5% compared to single-channel mode. This outcome is not really surprising, because if you look at the peak bandwidths of the new CPU's memory and FSB, you can see that the single-channel configuration is already sufficient to provide enough data to the CPU. The doubling of memory bandwidth thus has only a marginal effect on performance.

Of course, that's true in a configuration with dedicated graphics, such as we used at THG. If, however, the notebook uses the 915GM notebook chipset, dual-channel mode is definitely preferable to single-channel due to the greater bandwidth. Under these circumstances the GMA900 integrated graphics core takes up a considerable portion of the bandwidth for preparing video data, primarily when running graphics-intensive 3D applications. Unfortunately, there was no system of this type available at the time of launch for us to analyze. We will try to provide these results as soon as they can be obtained.

With the "old" platform using the 855PM notebook chipset, changing from DDR266 to DDR33 results in an up to 20% increase in speed, at least in synthetic memory tests like Wstream.

If you compare the new and old platforms in terms of performance, Sonoma comes out ahead of the Carmel in a number of benchmarks by a nose, while in others it ends up a tie, even though the Sonoma system with the Pentium M 770's CPU clock speed is 5% faster at 2.13 GHz. Our well-tuned "old" 855PM comparison system even wins in a few benchmark categories.

The new platform is up to 15% faster only in synthetic memory tests. At the end of the day, the new 915PM chipset-based platform is faster, but not by a lot.