According to the results obtained in SYSmark 2007 that estimates the systems performance in real applications during execution of specific tasks, the top Athlon II X4 processor model can provide about the same performance as the junior Intel CPU with four cores – Intel Core 2 Quad Q8200. This is a pretty good result, because AMD is going to sell their Athlon II X4 at lower prices than Core 2 Quad Q8200. However, you still shouldn’t consider these two CPUs equal, because they perform differently in different tasks. For example, during rendering or video content processing AMD processor can do better, while in office tasks and in applications for creation and processing of 2D raster and vector graphics Core 2 Duo demonstrates higher result.
By the way, in office tasks particularly the missing L3 cache has the biggest effect on Athlon II X4 performance. In these applications these processors yield even to previous generation Phenom X4, which work at significantly lower clock frequencies.
Moreover, it is important to understand that quad-core processors are not always better than their fellow brothers with fewer cores. Dual- and triple-core CPUs from the same price range work at higher clock frequency and that is why they work faster under those types of load that do not parallel well. For example, dual-core Core 2 Duo E7500 quite often takes leadership in SYSmark 2007.