We decided to create a little performance index by taking all the benchmarks into account. Since computing-intensive applications require the most horsepower, we weighted them at 50%, games at 25%, PCMark Vantage at 12.5%, and 3DMark Vantage at 12.5%. The result is a 5.8% performance benefit for the Phenom II X4 versus the Athlon II X4 or a 5.5% performance decrease if you use the Phenom II X4 as the basis. You probably have different priorities, so it’s important to point at minimum and maximum differences. Some benchmarks benefit by 20%; others don’t benefit at all. Yet, the 5% to 6% aggregate performance difference is the number you should remember.
Comparing price against performance makes it crystal clear that true budget-minded users shouldn’t (and probably wouldn't) consider the Phenom II X4. The Phenom II X4 945 (3.0 GHz) starts at $170, while the new sub-$100 Athlon II X4 trails fairly close behind on performance when all other system factors are equal. AM2+ models of the Phenom II X4 may start at $150 (Phenom II X4 940), but they don’t provide DDR3 support.
Overall, the main performance differentiator between the Athlon II X4 and the Phenom II X4 is clock speed. A simple 200 MHz increase for the Athlon II X4 would probably match the performance of a Phenom II X4, despite its large 6MB L3 cache. Knowing this, you can be sure that there will never be an Athlon II product that matches or exceeds the clock speeds of the premium Phenom II.
We believe it’s important to consider the different market segments that we inevitably blurred in this comparison. Phenom II is an upper-mainstream to high-end product at $150 to $250, while the Athlon II X4 targets the $100 audience. Still, it’s obvious that an Athlon II X4 provides a great value, especially for users willing to overclock the processor.
Finally, it remains to be said that L3 cache memory is imperative if you want to reach the highest performance levels. At the 2.6 GHz clock speed that we benchmarked, it may not be that obvious, but at 3 GHz and up we see the Phenom II scaling much better than the Athlon II X4.