Intel Core i7-875K and i5-655K Unlocked


Introduction and Specifications

Once upon a time, not very long ago in fact, Intel vehemently frowned upon overclocking. There were even times leading up to new processor and chipset releases when it was rumored that Intel would bring an end to overclocking altogether. Thankfully, the rumors of overclocking's death were greatly exaggerated and we enthusiasts continue to practice its black magic to this very day.

Intel's distaste for overclocking has obviously dwindled over the last few years, however. Whereas before, all of the company's processors were locked and its motherboards lacked overclocking options.  Now, Extreme Edition processors have unlocked multipliers and Intel motherboards have extensive overclocking tools built-in. It probably helps that Intel's current line-up of processor have massive amounts of frequency headroom left under to hood. But we digress...

Today Intel's takes its acquired taste for overclocking a step further. The company is announcing two new mainstream processor offerings, targeted squarely at overclocking enthusiasts and feature unlocked multipliers. The new Core i7-875K and Core i5-655K are virtually identical to the standard Core i7-870 and i5-650 from a technical standpoint, but with the right motherboard, users of these new K-series chips will be able to alter their multipliers to increase frequencies, without having to run any other part of the system out of spec.

Intel Core i7-875K and Core i5-655K Unlocked Processors
Specifications & Features

Intel Core i7-875K Processor Key Features:

  • Four Core Processing: Runs 4 independent processor cores in one physical packageRuns 4 independent processor cores in one physical package
  • Base Processor Frequency: 2.93 GHz
  • Intel Turbo Boost Technology:  Dynamically increases the processor frequency up to 3.60GHz when applications demand more performance.  Speed when you need it, energy efficiency when you don’t.
  • Intel Hyper-Threading Technology: 8 threads provide unprecedented processing capability for better multi-tasking and threaded applications. Do more with less wait time.
  • Intel Smart Cache: 8MB of shared cached allows faster access to your data by enabling dynamic and efficient allocation of the cache to match the needs of each core significantly reducing latency to frequently used data and improving performance.
  • Overclocking Enabled: Core (Turbo) and DDR3 ratios are unlocked for ease of overclocking
  • Integrated Memory Controller: Supports 2 channels of DDR3-1333 memory with 2 DIMMs per channel. Support for XMP memory.
  • Chipset/Motherboard Compatibility: Compatible with all P55, H57 and H55 chipsets. See your motherboard manufacturer for support details for these processors

Intel Core i5-655K Processor Key Features:

  • Dual Core Processing:  Runs 2 independent processor cores in one physical package
  • Base Processor Frequency: 3.2 GHz
  • Intel Turbo Boost Technology:  Dynamically increases the processor frequency up to 3.46 GHz when applications demand more performance.  Speed when you need it, energy efficiency when you don’t.
  • Intel Hyper-Threading Technology:  4 threads provide unprecedented processing capability for better multi-tasking and threaded applications. Do more with less wait time.
  • Intel Smart Cache:  4MB of shared cached allows faster access to your data by enabling dynamic and efficient allocation of the cache to match the needs of each core significantly reducing latency to frequently used data and improving performance.
  • Overclocking Enabled: Core (Turbo) and DDR3 ratios are unlocked for ease of overclocking
  • Integrated Memory Controller:  Supports 2 channels of DDR3-1333 memory with 2 DIMMs per channel
  • Chipset/Motherboard Compatibility: compatible with all P55, H57 and H55 chipsets. See your motherboard manufacturer for support details for these processors
  • AES-NI: Provides 6 new processor instructions that help to improve performance for AES encryption and decryption algorithms.


The new Core i7-875K and Core i5-655K are based on the 45nm Lynnfield and 32nm Clarkdale cores, respectively. We covered the main features and capabilities of these two cores at length here at HotHardware in the past, so we won't do the same again here. We would, however, recommend that you take a gander at these two recent articles:

In those two articles, we cover the specifications, features, and performance of both Lynnfield and Clarkdale and well as their companion motherboards and chipsets. Because the Core i7-875K and Core i5-655K are so similar to their locked counterparts, the information in those articles applies here as well.


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