Performance Summary and Final Thoughts
Performance Summary: In regard to the thermal and power characteristics of the new 65nm "Brisbane" core, AMD seems to have delivered on their claims of lower power consumption, which in turn translates into a higher performance per watt ratio than previous 90nm AMD processors. Strictly from a performance standpoint, however, the higher cache access latencies of the Brisbane core did translate into somewhat lower performance overall. With Synthetic testing, we did note lower performance in PCMark05's Memory test and SANDRA's Memory Latency Test. However, when we shifted our focus to performance testing with real-world applications, the actual differences reported were about 1-2.5% across the board.
From what we've seen in our testing, AMD delivers on their promise when it comes to a lower power CPU. In regards to both wattage draw and thermals, the new 65nm CPU was better overall than the same speed processor based on the older 90nm "Windsor" core.
Lower power also comes with slightly lower performance in the case of AMD's 65nm Brisbane core, however. In synthetic testing we saw the widest performance deltas, some of which hovered around 14.5% compared to the older CPU. Yet, when we shifted to real-world testing, the margins were a more marginal 1-2.5%. In the end though, slower obviously isn't better. However, in a side-by-side comparison, we think users would be hard pressed to actually "feel" the difference between the two processors. In fact, during our evaluation of the 65nm AMD Athlon X2 5000+, we ran the CPU in a normal work environment for several days and then switched it out with its 90nm counterpart and there was no obvious difference is day to day performance. In addition to this, the 65nm Brisbane core-based processor overclocked much better than the Windsor-core. And the higher overclock would easily offset the higher latencies. If you're in the market for a mid-range Athlon 64 X2 processor and plan to do some overclocking, look to the newer 65nm processors. Otherwise, if you're planning to run an AM2 system in an all-stock configuration one of AMD's 90nm processors offer slightly better performance.