AMD Phenom II X4 955

AMD has released two new high-end quad-core CPUs. The Phenom II X4 945 and 955 are Socket AM3 models with 6MB L3 caches and stock speeds of 3.0GHz and 3.2GHz respectively.

That makes them the company's fastest processors yet. When equipped with 4GB of DDR3-1066 RAM the 945 scored 1.85 in our 2D benchmarks, while the 955 managed an overall score of 1.92.

Those scores are significantly higher than the 1.71 achieved by the company's previous high-end chip - the AM2-based X4 940 running at 3GHz. Indeed, they're AMD's first chips to convincingly challenge Intel's Core i7-920, which achieved 1.86 in a comparable system.

What's more, since the 955 is a "Black Edition", its CPU clock multiplier can be freely adjusted to achieve even higher speeds.

Our sample ran stably at 3.7GHz with a standard heatsink and fan, returning a very respectable benchmark score of 2.17 - faster even than a Core i7-965 at its stock speed. And with specialist cooling, AMD reports Phenom II chips have been pushed up to an absurd 6.5GHz.

At the time of writing launch prices are unconfirmed, but AMD is aiming for a US OEM price of $255 for the 955 part - around £175 exc VAT. Factor in VAT and import costs and the two new chips look likely to straddle the £200 mark.

That would make the Core i7-920, which still sells for over £250 inc VAT, look decidedly overpriced.

It's good to see the Phenom architecture finally fulfilling its potential, even if it did take multiple revisions to get here. AMD still can't challenge Intel at the really high-end; as yet it has nothing to approach the power of an overclocked i7-965.

But these two new CPUs are the best way we've yet seen to get next-generation performance on a real-world budget.

Author: Darien Graham-Smith