Core i5 6600K processor review: Desktop Skylake

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The Skylake architecture

The Skylake Architecture

We'll address some key aspects and a technical overview of the technology and architecture first. Chances are good that you already have learned about this information over time. Right lets step back a few generations and start at Sandy Bridge at 32nm. Sandy Bridge really was a completely new architecture, its successor Ivy Bridge did share a lot of common denominators. When we look at Sandy versus Ivy Bridge, the foremost complicating factor was moving the architecture towards a smaller production node; Ivy Bridge is a 22 nm processor series. Haswell then, is a 22 nm product yet based on a FinFET process that uses a non-planar transistor that sits around the gate on three sides. Built using a 22 nm process, Haswell is the "tick" in Intel's "tick-tock" development cycle, so Ivy Bridge was just a process size shrink from Sandy Bridge's 32 nm to 22 nm.

Then a jump to 14nm, Broadwell is a Tick in the release schedule to be followed by a Tock, Skylake. For Skylake several things changed, an increasingly more powerful graphics engine and that fabrication shrink at the 14nm node, this allows for an even more power friendly processor.

Intel Core i5-6600K Processor Key Features

  • Intel Turbo Boost Technology 2.0:  Dynamically increases the processor frequency up to 3.9 GHz when applications demand more performance.  Speed when you need it, energy efficiency when you don’t.
  • Intel Smart Cache:  6MB 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.
  • CPU Overclocking Enabled (with Intel Z170 chipset):  Fully unlocked core multiplier, power, base clock and memory ratios enable ultimate flexibility for overclocking.
  • Graphics Overclocking Enabled (with Intel Z170 chipset):  Unlocked graphics multiplier allows for overclocking to boost the graphics clock speed.
  • Integrated Memory Controller:  Supports 2 channels of DDR4-2133 and DDR3L-1600 memory with 2 DIMMs per channel.  Support for memory based on the Intel Extreme Memory Profile (Intel XMP) specification.
  • PCI Express 3.0 Interface:  Supports up to 8 GT/s for fast access to peripheral devices and networking with up to 16 lanes configurable as 1x16, 2x8, or 1x8 and 2x4 depending on the motherboard design.
  • Chipset/Motherboard Compatibility:  Compatible with all Intel 100 Series chipsets with the latest BIOS and drivers.
  • Intel HD Graphics 530:  Integrated 3D performance with support for Microsoft DirectX 12 and Ultra HD 4K resolution display for immersive mainstream gaming.  For Microsoft DirectX 12 testing, the performance-tuned Intel graphics driver is expected to be available for download on Intel Download Center by the 6th generation Intel Core processor family product introduction.  The Intel HD Graphics 530 dynamic graphics frequency ranges up to 1150MHz.
    • Vibrant Media:  Enhanced, built-in visual features deliver a seamless visual PC experience for rich Ultra HD 4K entertainment and HD gaming.
    • Intel Quick Sync Video Technology:  Media processing for incredibly fast conversion of video files for portable media players or online sharing including support for HEVC (H.265) encode/decode to support Ultra HD 4K

Of course there will be a distinction per processor segment with the 5th generation (i3/i5/i7). What you get in terms of features and what you need to remember limitation wise:

  • Desktop Core i7 processors have four cores / eight hyper-threads / Up to 8 MB L3 cache
  • Desktop Core i5 processors have four cores / NO hyper-threading / Up to 6 MB L3 cache
  • Desktop Core i3 processors have two cores (unannounced)
All models will come with the latest revision turbo mode but only the Core i7 series will be capable of handling multiple independent software threads per core, also known as hyper-threading. It's a feature we like very much as it really helps out on peak performance by allowing a processor to execute two different code streams at pretty much the same time. 
MicroarchitectureCPU seriesTick or TockFab nodeYear Released
Presler/Cedar Mill Pentium 4 / D Tick 65 nm 2006
Conroe/Merom Core 2 Duo/Quad Tock 65 nm 2006
Penryn Core 2 Duo/Quad Tick 45 nm 2007
Nehalem Core i Tock 45 nm 2008
Westmere Core i Tick 32 nm 2010
Sandy Bridge Core i 2xxx Tock 32 nm 2011
Ivy Bridge Core i 3xxx Tick 22 nm 2012
Haswell Core i 4xxx Tock 22 nm 2013
Broadwell Core i 5xxx Tick 14 nm 2014 & 2015 for desktops
Skylake Core i 6xxx Tock 14 nm 2015

Core i 7xxx

Tock 14 nm 2016
Cannonlake Core i 8xxx? Tick 10 nm 2017

A lot of processors will be based on Skylake, the desktop side are actually the Skylake-S series, Skylake-Y series would power the Core M based processors for ultra low TDP devices, Skylake-U processors will be mainstream mobility devices and Skylake-H series are the high-end, performance focused mobility chips that will include both regular HQ variants along with Xeon processors for consumers demanding extra workstation capabilities on developer notebooks. But we focus on desktop, lets have a closer look.

Core Core i5-6600K and i7-6700K

Both models released are unlocked (multiplier & voltage) quad-core processors based on the afore mentioned Skylake architecture and supersedes the Core i7-4770 / 4790 processor range (in design). The Core i7 model has hyper-threading and your OS will see it as an 8-core product. The CPU has 1 MB L2 cache (256 kB per physical core). Then there is an 8MB shared L3 cache. The integrated memory controller remains dual-channel, officially supporting up-to 2133 MHz, but we all know how high these puppies can clock.  The TDP for this processor is now rated at 92 Watt. The Core i5 model is fairly similar product, yet clocked a notch slower at a 3.5 GHz base clock and 3.9 Turbo allowance. This processor as stated does not have hyper-threading. Also it has slightly less L3 cache at its disposal, 6 MB.

Core i7 6700K - 4 cores and Hyper-Threading, 4.0GHz frequency, 4.20GHz maximum Turbo Boost frequency, 8MB last-level cache, dual-channel DDR3/DDR4 memory controller with 1600MHz or 2133MHz support, Intel HD Graphics 530-series integrated graphics core, LGA1151 packaging

Core i5 6600K - 4 cores, 3.50GHz frequency, 3.90GHz maximum Turbo Boost frequency, 6MB last-level cache, dual-channel DDR3/DDR4 memory controller with 1600MHz or 2133MHz support, Intel HD Graphics 530-series integrated graphics core, LGA1151 packaging;

There will be more variants available later this year though:

Intel Skylake Desktop Processors Lineup
Model Process Cores Core Clock Boost Clock Cache Memory Support TDP Socket Unlocked Design
Core i7-6700K 14nm 4/8 4.0 GHz 4.2 GHz 8 MB DDR4 2133 MHz 91W LGA 1151 Yes
Core i5-6600K 14nm 4/4 3.5 GHz 3.9 GHz 6 MB DDR4 2133 MHz 91W LGA 1151 Yes
Core i7-6700 14nm 4/8 3.4 GHz 4.0 GHz 8 MB DDR4 2133 MHz 65W LGA 1151 No
Core i5-6600 14nm 4/4 3.3 GHz 3.9 GHz 6 MB DDR4 2133 MHz 65W LGA 1151 No
Core i5-6500 14nm 4/4 3.2 GHz 3.6 GHz 6 MB DDR4 2133 MHz 65W LGA 1151 No
Core i5-6400 14nm 4/4 2.7 GHz 3.3 GHz 6 MB DDR4 2133 MHz 65W LGA 1151 No
Core i7-6700T 14nm 4/8 2.8 GHz 3.6 GHz 8 MB DDR4 2133 MHz 35W LGA 1151 No
Core i5-6600T 14nm 4/4 2.7 GHz 3.5 GHz 6 MB DDR4 2133 MHz 35W LGA 1151 No
Core i5-6500T 14nm 4/4 2.5 GHz 3.1 GHz 6 MB DDR4 2133 MHz 35W LGA 1151 No
Core i5-6400T 14nm 4/4 2.2 GHz 2.8 GHz 6 MB DDR4 2133 MHz 35W LGA 1151 No

The Skylake cache memory consists of a 32 KB L1 Data cache, 32 KB Instruction cache (= 64 KB L1) and then we spot a 256 KB L2 cache per core (1MB total) and then there's a L3 cache that is shared in-between the CPU cores which is 8 MB in total for the Core i7 processors and 6 MB for the Core i5 series. The L3 cache sits in the physical form of a ring-bus. Thus the L3 cache can be used by the processor cores and also the graphics core. You can house the new Skylake processors on motherboards with the H170 and Z170 chipset and will be introduced later on other business oriented chipsets as well. So no, the H97/Z97 chipset is not compatible! For end consumers like you and me the H series chipset is less performance targeted and comes with better support for HTPC monitor connectivity. The Z series chipset is targeted at performance and enthusiast end users allowing much more tweaking and providing performance features. It also brings USB 3.1, SATA Express and PCIe M.2 SSD connectivity to the platform. 


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