Intel Core i5-655K & Core i7-875K Unlocked Processors Review

Author: Patrick (MAC) MacMillan
Date: May 27, 2010
Product Name: Intel Core i5-655K & Intel Core i7-875K
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Intel Core i5-655K

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As you can see from this slim box, the rumours that Intel would bundle a variant of the DXB-B cooler, that was launched with the Core i7-980X, with these K-series processors is false. We have no problems with this omission since enthusiasts should be absolutely be using third-party cooling solutions, especially with processors designed for overclocking.

As is visible on the box, these K-series processors do also come with a 3-year warranty. Therefore, we can assume that Intel is OK with consumers overclocking these particular models. That should please the worriers who don't overclock merely due to a fear of voiding their warranty.

Now the Core i5-655K obviously falls within the Core i5-600 series 'Clarkdale' LGA1156 family, but just
in case you aren't familiar with Intel's naming scheme here is a recap: Intel have chosen their Core i3/5/7 brands to help highlight the number of threads and specific technologies that each processors series supports. Simply put, Core i7 models are eight-thread processors which feature both Hyper-Threading (HT) and Turbo Boost technology. The Core i5 models are four-thread processors with Turbo Boost. The Core i5 series will now be particularly confusing to consumers though, since it is comprised of the 4-core/4-thread i5-700 series and the brand new 2-core/4-thread i5-600 series. Then we have the Core i3-500 series models, which are 2-core/4-thread processors but without Turbo Boost. Lastly, we have Pentium G6000 series, which will be dual-core processors without Turbo Boost or Hyper-Threading.

It is quite a mishmash, but thankfully we are only interested in the Core i5-600 series models on this page. The tables below should help provide greater insight about the various Core i5-600 'Clarkdale' variants.

As you can see, the Core i5-655K is effectively identical to the Core i5-650. They both have exactly the same specifications in every respect, except for the obvious fact that the Core i5-655K has unlocked multipliers. The K-series chip also carries a not insignificant $40 price premium. Whether unlocked multipliers are worth the $40 really depends on whether you are a 'set it & forget it' overclocker, or someone who enjoy's tweaking all the time. The price increase is not that bad though since at $216 Intel are knowingly decimating the potential sales of the $284 i5-670.

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There's nothing particularly unique about the exterior of the new Core i5-655K, it is identical to every other LGA1156 processor on the market. Obviously our chip is an engineering sample, but otherwise what you see is what you get.

For those of you who are interested, our particular sample was manufactured in the 4th week of 2010.

Click on image to enlarge

The connoisseurs among you should already have noticed that the Core i5-655K features a brand new core revision. While current Clarkdale processors are all based on the C2 revision, this new chip features the updated K0 revision. Normally this would indicate eight respins, but that doesn't seem likely (or necessary) in this case since there was nothing actually wrong with Clarkdale's core, as far as we know. Obviously we are all hoping for improved overclocking headroom, and we will find that out in the coming pages.

If you aren't familiar with the particulars of the Clarkdale microarchitecture, want to know more about the various models, or perhaps the integrated GPU, we highly recommend that you take a peak at our original Clarkdale review article. It should answer any and all questions.

Now letís take a look at the second K-series processor that Intel is launching at Computex next week, the very interesting Core i5-875K.

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