Labs

Intel's flagship family of processors is the Conroe-based Core 2 Duo, and it's a stunning piece of technology. Shifting the focus firmly away from the clock-speed race of previous families, the Core 2 is a streamlined, ultra-efficient beast that's equally at home in a gaming powerhouse as in a quiet media centre PC.

Using the 65nm fabrication process, it has a TDP (thermal design power) of just 65W, which, amazingly, is almost as low as a Sempron and half the power requirement of a Pentium D 960. All current models boast a front side bus frequency of 1,066MHz, a speed previously found only in Extreme Edition CPUs. The new ICH8 memory controller supports 800MHz memory, and you'll see a worthwhile increase in performance over 667MHz RAM.

The range begins with the E6300, which is clocked at 1.86GHz, and the E6400 at 2.13GHz, both of which have 2MB of shared Level 2 cache. Then there are the E6600 and E6700, clocked at 2.4GHz and 2.66GHz respectively, both with 4MB of shared Level 2 cache.

This shared cache is one of the key features of Core 2 CPUs and means each core can grab as much as it needs whenever it needs it, rather than strictly allocating half to each. This effectively gives you a single-core CPU with 4MB of cache whenever the situation demands.

Other notable features include virtualisation, 64-bit support - courtesy of Intel's EM64T instructions - and Intel's new "wide dynamic execution". This means that every stage of the instruction fetch, code and execution system is wider than before, allowing it to cope with up to four standard

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instructions simultaneously. It also shortens the pipeline and allows the Core 2 to search further ahead to find instructions it can execute in parallel to keep all four paths fully utilised.

Value for money

Put simply, every one of the Core 2 Duo processors offers great value, as the graph on p94 clearly shows. The E6300 is the least impressive, yet happens to fall in very closely with AMD's X2 range in terms of price and performance, achieving an Overall score of 1.16 in our benchmarks for £106.

If you have a compatible motherboard, the E6300 is an infinitely better choice than all but the cheapest Pentium D processors. For similar money, you'd get a maximum score of 1.05 from a Pentium D 945; add in the increased energy efficiency of the Core 2 Duo and the decision is a no-brainer.

At the top end, the E6700 is a phenomenal performer, scoring 1.61 in our benchmarks. At around £300, it's more expensive than all but the Extreme Edition CPUs of other ranges, but - although there's no Athlon 64 X2 CPU that can match this performance - a theoretical match for the E6700 would cost a lot more if we were to extend the Athlon X2's trend line on our scatter graph. However, for all but the most enthusiastic system builders, the E6700 is too expensive compared to the E6600 and E6400.

The E6600 is more affordable at £192, and with an Overall score of 1.43 it's no letdown in the power department. If your budget will stretch to this price, it's a great choice - well illustrated by the fact that AMD's flagship FX-62 performs similarly but costs more than twice as much.

But if value for money is the prime criterion in choosing a CPU for your PC, there's surely only one model to consider. Costing just £130, the E6400 has the perfect blend of power and price. Before the launch of Core 2 Duo, you'd have had to spend at least twice this price to get a similar score of 1.29 - it simply walks over every other CPU here for value.

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