Based on the same core as the Athlon II series, but with a meaty 6MB of L3 cache, the Phenom II is AMD’s premium brand. It’s an old one, though.
Running at stock speeds, the top quad-core Phenom II chip only just keeps up with Intel’s entry-level Sandy Bridge Core i3 processors. Frankly, the Phenom II doesn’t have much of a future: we expect it will be retired shortly after AMD unveils its next-generation Fusion desktop platform this summer.
That doesn’t mean you should reject the Phenom II. The chips are priced to compete with Intel’s mid-range offerings and motherboards are affordable, so the platform could be a good choice if you’re building a system on a tight budget. Many boards come with an integrated GPU. The Phenom II series doesn’t have graphics built into the processor – that’s set to appear with Fusion.
Although AMD chips can’t compete with Intel’s best, we found Phenom II chips achieved respectable scores in our Responsiveness and Media benchmarks. Multitasking performance starts low with the dual-core models, but more power exists in the quad-and six-core units.
What makes things interesting is that most current models are Black Edition chips, which means their clock speeds are unlocked and can easily be adjusted using the BIOS. For example, you can accept the X2 550 Black Edition’s default 3.1GHz speed, or boost it to 3.4GHz to simulate an X2 565. In principle, you can go even higher (see p65).
The six-core models can dynamically increase their speed when not all cores are in use, using a system AMD calls Turbo Core. It’s the same idea as Intel’s Turbo Boost, giving these models an advantage for single-threaded tasks as well as multithreaded ones.
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Which one should you buy?
The current Phenom II line-up is uninspiring at stock speeds; for the X2 chips at the bottom end, you’ll get better value from an Athlon II processor. At the top end, the six-core models are priced to compete with the latest Core i3 and i5 processors, although unless you do a lot of multicore processing, you’ll get better performance from the Intel chips.
The best performer for its price is the Phenom II X4 955. It’s hardly state of the art, but it has enough grunt to make a decent fist of media and multithreaded tasks for only $148.
If you’re happy to delve into your BIOS and take advantage of an unlocked chip, things get more interesting. AMD doesn’t make any overclocking promises, but a low-end Black Edition should match the mid-range models quite happily. That means there’s no need to invest in a top-end chip such as the Phenom II X4 975: stick with the X4 955 Black Edition instead and simply push the clock as far as you can to get strong all-round performance at a much more attractive price. It’s a similar story with six cores. A Phenom II X6 1075T Black Edition should approach or equal the 3.3GHz 1100T for about $35 less.
Sadly, you probably won’t get a Black Edition to run much more quickly than the models that are already offered – at least not without specialist cooling equipment. These 45nm chips are prone to overheating if you push them too hard, leading to system crashes.