Intel Core i7-900s are rated for top speed, but are better suited to enthusiasts

 The now-defunct Core i7-965 Extreme blew our benchmarks away, before the range extended in both directions to comprise the five models on sale today.

Requiring an expensive Socket LGA 1366 motherboard, these quad-core parts range from the 2.66GHz i7-920 to the new 3.2GHz i7-960 - as well as the top-end Extreme part, the multiplier-unlocked 3.33GHz Core i7-975.

The i7 re-introduced Hyper-Threading - a standard feature of Pentium 4 processors, but absent from the Core series. They offer 8MB of shared cache, a 4.8GT/sec QPI bandwidth (6.4GT/sec for the Extreme) and a whopping 130W TDP.

All support virtualisation, and they also make use of Intel's Turbo Boost system: idle cores are automatically clocked down, and the power saved is used to dynamically overclock busier cores.

It means the CPU remains efficient for multithreaded tasks, while giving single-threaded applications a significant speed boost (see page 67 for Turbo Boost frequencies).

The Core i7 CPUs are undeniably fast - the i7-975 Extreme scored a huge 2.19 - but the issue is price. The i7-920 will set you back $352 for a score of 1.86, and that's before you add the cost of a motherboard.

AMD's top models are far more affordable, and Intel's own Core i5-750 (see page 66) offers much that these chips do at a far more attractive price. You'd have to be feeling pretty flush to take the plunge on an LGA 1366 part at this early stage.

CPUs rated and reviewed: click on image for larger size

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