Because our focus is on Yorkfield core overclocking advantages compared to previous Kentsfield core capabilities, we used the Core 2 Extreme QX6850's base speed as a reference point for comparing each configuration. We'll begin with the game tests.
Most games can't take advantage of four cores, but we noticed two that did benefit slightly from the newer core technology. Yet when we average the performance difference of all three game tests, the Core 2 Extreme QX9770's 6.6% default clock speed advantage gave it only a 6.2% win over the default-speed QX6850. Overclocking was the point of this comparison, and the QX9770's better overclocking capabilities stretched its lead a bit farther.
Applications are where we really expect the Core 2 Extreme QX9770's newer technology to shine, especially when it's also clocked higher.
The QX9770 leads the QX6850 by over twice its clock speed difference before overclocking, and its greater overclocking capabilities continue to outpace the elder part by similar amounts. The dual-core E6750 lags behind the QX9770 by around 30% in both default and overclocked configurations.
Synthetic benchmarks are often accused of providing a false sense of reality, yet many buyers compare them across various websites. Because these often pinpoint a single function, they also serve the practical purpose of exposing particular strengths and weaknesses.
The QX9770 shows fairly large gains compared to the QX6850 in average synthetic performance testing, but these gains are still lower than those previously seen in actual applications. The E6750 also does far worse than previously noted, probably because synthetic CPU tests are better than typical applications at targeting the total number of CPU cores.
An average of all performance differences will help to indicate the performance "feel" of each system.
If you use your system for an extremely wide variety of tasks, the Core 2 Extreme QX9770 will appear to be around 12% faster than the QX6850. A similar gain could be had for a much lower price using the overclocked E6750, but the QX9770 overclocks still further, to beat even the highest of our QX6850 results by around 11%.