AMD Phenom review

AMD's Phenom range has expanded a great deal since our processor Labs last year, from the triple-core Phenom X3 8450, which costs just £72, to the powerful and versatile 2.6GHz Phenom X4 9950 Black Edition.

Each core of a Phenom processor has 128KB of L1 cache, consisting of 64KB for data and 64KB for instructions, and 512KB of L2 cache. The processors also have an additional 2MB of L3 memory cache, which all the cores share. With the release of Intel's Core i7, this feature is no longer unique to the Phenom, but it still provides an advantage over Intel's similarly priced Core 2 Quad processors, which don't have this cache, resulting in more memory operations.

Phenoms are available in three- and four-core versions. Phenom X3 processors use the Toliman core and are part of the 8000 series, while the quad-core Agena processors make up the 9000 series. Although Phenom processors are backwards compatible and work with AM2 motherboards, to make the most of your processor you'll need the faster HyperTransport 3 interconnect technology found on AM2+ motherboards to run the HyperTransport bus at it's full speed of 2,600MHz.

Specific processors

Early Phenoms were slow compared with Intel processors in the same price range, but recent additions to AMD's range prove that some Phenom processors can compete with Intel's Core 2 Quad chips at lower prices.

If you're after a mid-price processor, AMD's triple-core Phenom X3 processors provide comparable performance to similarly priced Core 2 Duos and also outperformed several of the slower quad-core Phenoms. The Phenom X3 86750 is a decent budget processor, although the cheaper triple-core Phenoms can't quite match budget Intel processors such as the Core 2 Duo E7300 for value.

Standard Phenom processors have a Thermal Design Power (the maximum amount of heat a cooling system will have to dissipate) of 95W and 140W. AMD is also launching energy-efficient Phenoms that will have a TDP of 65W. These processors are more suitable for use in small desktop systems, which don't have the same level of cooling as large desktop cases. One of the first lower-power chips is the X4 9350e. Unfortunately, a high price and low 2GHz clock speed make this processor a poor choice, and Intel's Core 2 Duo E5200 is better.

One of the most impressive processors here is the new Phenom X4 9950 Black Edition. Its multiplier is unlocked, which will please anyone who wants to overclock their system. Even at its default clock speeds it outperforms or equals the performance of the similarly priced Intel Core 2 Duo E8400 and Core 2 Quad Q6600 chips, which makes it a strong Best Buy.