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Overclocking Haswell processors: How and when to do it

Intel introduced its latest-generation processors this year. The Haswell generation also contains two K processor that are aimed specifically at overclockers. In today's workshop we'll show you how to get maximum performance from your Haswell CPU.

Overclocking Haswell CPUs is largely the same as with the previous generations, Sandy Bridge and Ivy Bridge. Of course there are some differences, such as the integration of voltage regulators in the CPU and the introduction of so-called baseclock straps. In this article we'll cover the basics of overclocking, along with specific instructions for motherboards from the four main brands (ASRock, ASUS, Gigabyte and MSI).

The clock frequency of a processor is the product of the base clock frequency (base clock or bClk) and a so-called multiplier. For Haswell boards, the bClk is standard 100 MHz, just like on Sandy Bridge and Ivy Bridge. With a CPU multiplier of 42, that translates to 42 x 100 = 4200 MHz = 4.2 GHz. You can overclock in two different ways, either by increasing the base clock frequency, or by increasing the multiplier. Like previous generation CPUs, the bClk can vary by about 5 per cent at most. A very small amount of chips can run at 106 MHz, 107 MHz or even higher, but for the majority of CPUs 104 or 105 MHz is the limit. That means that overclocking the CPU is primarily done by increasing the multiplier. That's only possible with the K processors, specifically the Core i7 4770K and Core i5 4670K. Any other Haswell processor is limited to playing around with the bClk, so you can't really overclock much.

In a processor there are several multipliers, since different components of the chip work at different speeds. The CPU cores already have multipliers, with a standard value and four Turbo multipliers, that determine the maximum speed of the CPU when one, two, three or four cores are active. You can read rest of the How to overclock Haswell processors on