2. Does Napa Taste Better Than Sonoma?

To compare the newer Centrino Duo chipset (945GM) to its predecessor the Centrino (Sonoma) 915GM, we selected two ultra-portable notebooks with 12.1" widescreen displays from Asus for comparative tests. Beside their platforms, the Asus W5F and W5A are otherwise identical, in order to demonstrate the performance differences between the two CPU/chipset combinations. We also ran some of our individual tests using three different Pentium M processors (Pentium M 730, 750 and 760) as part of our comparative tests.

945GM Versus 915GM

The 945GM is a member of the mobile Intel 945 Express chipset family, code named "Calistoga."

In addition to Core Duo CPUs that feature faster front side bus speeds and a maximum of two CPU cores, Calistoga also supports nominally faster and more energy efficient DDR2-667 memory for use in laptops. Slower and less energy efficient DDR modules won't work with this chipset. SATA interfaces, Intel's High Definition Audio and the Express Card I/O interface are all part of Calistoga/945GM's as well, but they were already available with the Sonoma/915GM platform.

The graphics core of the 945GM is based on the 950 Graphics Media Accelerator (GMA), which is also used in mainstream desktop chipsets, such as the 945G and the 945GZ. This graphics core is DirectX 9 compatible, but not entirely DirectX 9 compliant.

Like the GMA900, the GMA950 makes a total of four actual pixel pipelines available. Other graphics processing features, such as the vertex shader, must be emulated on the CPU instead. In contrast with other graphics processors that implement DirectX 9 completely in hardware, such as ATI's Mobility Radeon X300 or Nvidia's GeForce Go 6200, the performance of the GMA950's vertex shader and thus, overall 3D performance, hinges on CPU power and capability. 3D graphics performance, thus, scales directly with CPU clock speeds.