Quad-core processors are the most capable, and doubly so when you consider the effect of Hyper-Threading. This lets recent software operate as if it was running on an eight-core processor. The Intel parts we’ve tested here are the middle-order Core i7 chips running at 2.3GHz (3615QM) and 2.6GHz (3720QM). An added speed boost is provided by Turbo mode, which allows short-term auto-overclocking on a single core to 3.3GHz and 3.6GHz respectively.
The down side of these chips is higher power consumption and greater heat output. But even with their 45W thermal design power (TDP) we’re finding comparatively cooler and longer-running laptops than last year’s already impressive Sandy Bridge generation.
For the thin-and-light brigade, very low battery drain and minimal surplus heat are paramount. Filling that need for ultraportables are Core i5 processors with a U suffix (for ultra-low voltage), such as the 1.7GHz 3317U. This is the processor chosen by Apple for its MacBook Air and Samsung for its Series 9.
Between the fastest quad-core Core i7 and the most frugal Core i5 ‘U’ series is a range of dual-core chips. The Dell Inspiron 15R, for example, takes a 2.5GHz Core i5-3210M.
Note the names Intel uses to market its processors, where a Core i7 can be a quad- or dual-core chip, while Core i5 for mobile are always dual-core. Unlike earlier generations, all i5 and i7 chips include Turbo and Hyper-Threading. There is now only one Core i3 listed by Intel, the 1.8GHz 3217U, which omits Turbo mode.
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Any Ivy Bridge processor will unlock terrific speed and great battery economy. If your needs include video editing, virtualisation or workstation activities, you’ll likely benefit from a QM version.