in: Features - Processors | July 3, 2010 | by: Oik Yusuf Araya

i7 875K: A More Affordable, Unlocked Version of an Intel Processor

It’s no secret that over clocking has set a trend for computer users everywhere. Back to the times when processors, or CPU, came with unlocked multiplier, over clocking was as simple as counting 1-2-3. A multiplier change was all it takes to bump the speed a notch or two, sometimes even way more. When the multiplier went locked as the logical consequence from the wide spreading of such practice, over clocking became much more complicated.

Not too long ago, Intel, one of the two main manufacturers of desktop computer CPUs, began marketing unlocked versions of their processors, dubbed the Extreme Edition series. Unfortunately, they come at a premium price point, making unlocked processors a luxury only few could ever afford. Now, that condition is about to change. We have obtained a sample of their more affordable unlocked processor, the Core i7 875K.

Intel Core i7 875K

What’s all the fuss about processors with unlocked multiplier? Well, a processor’s speed is determined by the base clock (formerly known as the Front Side Bus), multiplied by a factor (the multiplier) to generate its effective working frequency. For example, at 2,93 GHz, the Core i7 875 operates at 133 MHz base clock multiplied by 22 (133 x 22 = 2926 MHz). If the multiplier is locked, you cannot change this multiplier factor into a higher value, like, say, 23 to increase the frequency. You can step it down to a lower number, but that would slow the processor down instead of speeding it up. You can also increase the base clock frequency, but it will affect other peripherals as well, such as your memory speed that will go up linearly along with the base clock increase, whereas a multiplier change would only affect the processor itself. Nothing else is involved, lesser parameters to complicate your life with. That’s the convenience of over clocking a processor with an unlocked multiplier, and that’s why Intel had been allocating this capability exclusively to their top-of the- line series, limiting the over clocking potentials of cheaper processors, until recently that is.

Actually, Core i7 875K was not the first unlocked processor that is not included within the Extreme Edition ranks. There was the Intel Pentium E6500K, which rather unfortunately was reserved for the market in China only. Anyway, let’s have a look at Core i7 875K’s technical specification.

Specification Sheet

Intel® Core™ i7 870 Intel® Core™ i7 875K Intel® Core™ i7 930
Code Name Lynnfield Lynnfield Bloomfield
Number of Cores 4 4 4
Number of Threads 8 8 8
Clock Speed 2.93 GHz 2.93 GHz 2.8 GHz
Max Turbo Frequency 3.6 GHz 3.6 GHz 3.06 GHz
L3 Cache 8 MB 8 MB 8 MB
Bus/Core Ratio 22 22 21
Instruction Set Extensions SSE4.2 SSE4.2 SSE4.2
Fabrication Process 45 nm 45 nm 45 nm
Memory Types DDR3 DDR3 DDR3
Memory Channels Dual Dual Triple
Sockets Supported LGA1156 LGA1156 LGA1366

The letter “K” in the end of the name indicates that this series of processor has an unlocked multiplier. Aside from that, there isn’t any significant difference with Core i7 870, its older sibling whose multiplier is unsurprisingly locked. Other technical specs, such as the frequency, turbo frequency, cache amount, and fabrication process, remain similar as well, if not precisely alike. It’s almost like the Core i7 875K is an unlocked version of Core i7 870.

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