AMD's Phenom X4 integrates four cores onto a single die, each having access to both an individual 512KB cache and a shared 2MB L3 cache. It's more efficient than Intel's approach, and HyperTransport 3 lets the Phenom access system RAM at a blazing 3.6GHz (motherboard permitting).
Unfortunately, this doesn't translate into real-world performance: in our benchmarks, the Phenom 9600 tied with a dual-core Athlon 64X2 6000+ costing a third less. Give the applications a few years to catch up with multi-core technology and the Phenom might come into its own, but for now, it's a disappointment.
Even if you need a multi-core system, the Phenom doesn't distinguish itself. Intel's quad-core parts may be less elegantly engineered, but they compensate with larger data caches and faster clock speeds. The Core 2 Quad Q6600 outran the Phenom 9600 outran the Phenom 9600 by more than ten per cent in our benchmarks for a very similar price.
And as with the Athlon, if you demand even more horsepower, there isn't currently a Phenom for you. The current range maxes out at a benchmark score of 1.28, while Intel's quad cores go up to a whopping 1.77.
But there's hope for the Phenom yet. As we went to press, AMD was unveiling two new Phenoms, the X4 9750 and X4 9850. These new B3-revision chips raise clock speeds to 2.5GHz, and if the price us right they could shake things up.
At the same time, AMD has also announced a range of triple-core Phenoms – actually quad-core parts, in which one core is faulty and has been disabled. Look out for our verdict on the new Phenoms next month.
All Phenoms embody some neat ideas, not least a new implementation of AMD's Cool 'n' Quiet system which dynamically throttles individual cores to keep temperatures and power consumption to a minimum, but the real-world performance of the current line-up doesn't justify the price.