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Review: Intel Core i7 875K and Core i5 655K - unlocked chips for enthusiasts

by Tarinder Sandhu on 28 May 2010, 05:00 3.0

Tags: Core i7 875K, Intel Core i5 655K, Intel (NASDAQ:INTC)

Quick Link: HEXUS.net/qayis

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Overclocking the duo

875K

The Intel Core i7 875K is, as we've said, practically identical to the 870 model that ships in reasonably high-end desktops.

875K

Idling at 1.2GHz and Turbo Boosting up to 3.6GHz when a single core is used, the fun starts once you add a little voltage.



Cooled by a Thermalright Ultra Extreme and 120mm fan, we increased the Vcore from 1.175V to 1.325V and then increased the mulitplier until failure. The chip was rock-solid stable with a 31x multiplier (4135MHz) but exhibited the odd stability problem at 32x (4,258MHz). Under-load temperature hit 74°C, according to the motherboard's PCProbe software, and the overclocking headroom may well be compromised by heat-related issues as much as the frequency ceiling.

655K

Much like the 875K, the 655K does a perfect job of replicating a Core i5 650 chip when put straight into a motherboard, running at 3.2GHz and Turbo Boosting up to 3.46GHz.

655K

Give it some love by increasing the voltage to 1.32V, resulting in an under-load temperature of 59°C, and the chip nears 4.5GHz.

655OC

A little unstable with a 34x multiplier (4,549MHz), a 1.2GHz overclock over default frequencies is decent for the dual-core, quad-threaded chip. Expect more if you put some really heavy-duty cooling on it.