The fastest and also the most efficient processor is Intel's Core 2 Duo. We selected an upper mainstream model as our reference CPU: the Core 2 Duo E6850 at 3.0 GHz core clock speed and FSB1333 system speed (333 MHz bus). This 65 nm processor is based on the Conroe core, which was introduced in the summer of 2006. With 4 MB of united L2 cache and two processing cores, it provides excellent performance at an acceptable cost. The Core 2 Duo E6850 can typically be overclocked to at least 3.4 GHz, and many users have been reporting up to 4 GHz in various forums.

We also looked at the Core 2 Quad models, which are available at speeds of up to 2.66 GHz. Depending on the type of review, we might also use one of these. However, looking at how applications currently scale from two to four cores, we did not see the necessity of going for a quad core processor right now. The next generation reference system will certainly be based on a quad core chip, which could be based either on AMD's upcoming 45 nm quad core called Deneb (Socket AM3, 6 MB L3 cache, DDR3-1600+) or Intel's Core 2 successor currently code-named Nehalem. The latter will be a native quad core with a DDR3 memory controller on die. Since both are still more than half a year away, we'll stick to the Core 2 Duo E6850 as our reference for now.