At the beginning of the tests for this project, we had a hunch that the resulting curves of the P4 Prescott and those of the Northwood processor would cross in several benchmarks. This was based on the assumption that Prescott, thanks to the double cache size and the 31-part pipelines, could produce more performance at a higher speed than the Northwood processor.
From this perspective, the results are sobering, because even at 4 GHz little changes in the balance of power between the two cores. Northwood is and remains the faster processor in common applications, even if the difference can be virtually ignored in application.
However, our scaling analysis has a slight disadvantage: Raising the FSB speed to up to 260 MHz increases the operating speed of the whole system and even that of the RAM. The Prescott's touted advantage, its 1 MB L2 cache, is thus less noticeable than it would be at a constant 200 MHz FSB speed.
The lesson to be drawn from this is that whenever the core speed - and only the core speed - is increased, the Prescott will always be slightly ahead of the Northwood core. Therefore it will scale better, but it cannot deliver the added performance that Intel touts.