How Well Does Phenom Scale With Clock Speed?
When we compared AMD’s Athlon 64 X2 and the new Phenom 9000 quad core processor last month, Compare Prices on AMD Phenom Processors we forced Windows to utilize only a single processing core, in an effort to understand the real performance differences between the AMD64 architecture and the Stars architecture of the Agena/Barcelona core. Depending on the particular benchmark, the results made clear that Phenom is indeed up to 20% faster than Athlon in a core to core comparison, thanks to its optimizations and the L3 cache. In addition to these performance gains, Phenom’s unified quad core design and smart cache architecture should provide more benefits under heavily threaded conditions. We haven’t looked at the performance difference using all processing cores, as you will find this information in our launch article "Phenom 9700, AMD’s 1st Quad Core CPU". All benchmark results, including a comparison with all Core 2 processors, can be found in our Interactive CPU Charts.
While the core to core analysis provides interesting results about architecture performance across typical benchmarks, it does not answer the question that will eventually be crucial, once Phenom’s TLB issues are fixed (B3 stepping) and the chip is available at higher clock speeds in quantities. The question is simply whether the quad core will scale well enough to attack Intel at the high end. In other words : Will clock speed increases translate into higher performance gains than just similar clock speed increases with an Athlon 64 X2 ? And at which clock speed will power consumption become an issue ?
Of course we wanted to get some answers, so we grabbed our test system again : the Asus M3A32 MVP using AMD’s 790FX chipset, an Athlon 64 X2 6000+ processor, a Phenom 9000 engineering sample (unlocked) Compare Prices on AMD Phenom Processors , two 1 GB DDR2-800 DIMMs by Corsair, our Western Digital reference hard drive, and Gigabyte Radeon HD3850 reference graphics card. We ran both processors at 2.2, 2.4, 2.6 and 2.8 GHz clock speeds, to see how well the clock speed increase translates into additional performance.