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Performance-Enhancing Changes

AMD Phenom II X4: 45nm Benchmarked
By , Frank Voelkel

Compared to the first-generation Phenom processors, the Phenom II is faster clock for clock. AMD cites four key areas that were enhanced, in addition to the silicon-level transistor changes previously mentioned, that help Phenom II deliver increased processing speeds.

1. More Instructions Per Clock Cycle

The Phenom is built upon the Stars architecture, but its implementation includes numerous improvements undertaken to increase the number of instructions that can be handled per clock cycle. No new instructions or multimedia extensions were needed to achieve this speed-up. By comparison, the first-generation Phenom processors added support for the SSE4a multimedia extensions, which the Athlon 64 X2 processors do not share.

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2. Increase In Clock Rate 

As a result of the switch from 65 nm to 45 nm manufacturing, the voltage needed to drive Phenom II is down significantly. In combination with an improvement to the base micro-architecture, this gave AMD a license to increase the clock rate. Whereas the first-generation Phenoms topped out at 2.6 GHz, the latest Phenom IIs start at 2.8 and scale to 3.0 GHz.

3. Increase The L3 Cache To 6 MB

It just wasn’t an option for AMD simply to arm the first-generation Phenom with a larger L3 cache. The power requirements of those 65 nm transistors would have undoubtedly boosted consumption past the 140 W mark. But current draw was sufficiently reduced in switching to 45 nm technology to enable AMD to augment the L3 cache size from 2 MB to 6 MB. In any case, the separate 512 KB caches provided for each individual core did not change with this redesign, nor did the 64 KB L1 instruction and data cache areas.

4. Support For DDR3-1333 RAM

Another contributor to the Phenom II’s improved performance comes from its support for DDR3 RAM, though it won’t be available for a few months yet. AMD plans to introduce the Phenom II with this RAM interface together with the market introduction of its Socket AM3 architecture.

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