Intel Skylake Core i5-6600K & Core i7-6700K Review

👤by David Mitchelson Comments 📅05-08-15
Skylake Features & Specifications

We want to preface this section with a short statement. Intel’s initial release schedule for Skylake was planned well in advance, long before Microsoft officially announced the launch date of Windows 10. Most of August was set aside for conferences and seminars including the Intel Developers Forum in San Francisco, all with the aim of taking the wraps off and going deep into the technology within this new CPU architecture. Unfortunately bringing forward the release date of ‘K-series’ SKUs has meant that they’re unable to furnish detailed technical info to reviewers and members of the press, and won’t be releasing this information until IDF. The following is information which has been released thus far.


Technical Specs

Intel Core i7 6700K

- 4 Physical Skylake cores, supporting Hyperthreading (8 logical cores)
- 4 GHz Base Clock, 4.2 GHz Turbo Mode
- 8 MB L3 cache
- Intel HD 530 Graphics
- Socket LGA1151
- Fully Unlocked Multiplier
- DDR4 and DDR3L support
- Supports DDR4-2133 and DDR3L-1600 (non-OC)
- 16 PCI-Express 3.0 lanes
- 91W TDP
- Hardware support For DirectX 12
- H.265 Encode/Decode

Intel Core i5 6600K

- 4 Physical Skylake cores (4 logical cores)
- 3.5 GHz Base Clock, 3.9 GHz Turbo Mode
- 6 MB L3 cache
- Intel HD 530 Graphics
- Socket LGA1151
- Fully Unlocked Multiplier
- DDR4 and DDR3L support
- Supports DDR4-2133 and DDR3L-1600 (non-OC)
- 16 PCI-Express 3.0 lanes
- 91W TDP
- Hardware support For DirectX 12
- H.265 Encode/Decode


Skylake is the second of Intel’s CPU architectures to make use of a 14nm fabrication process, but unlike Broadwell includes far more significant revisions to the underlying microarchitecture when compared with the previous generation. Due to these revisions, both on the CPU and motherboard chipset, it makes use of a new LGA socket specification (LGA 1151).

Perhaps the most significant change from a user perspective will be the use of DDR4 memory on the mainstream desktop platform. Skylake features a memory controller capable of operating with either DDR4 or DDR3L, but Intel belive that only DDR4 is likely to be a part of 3rd party vendor implementations on desktop motherboards. DDR4 brings with it far greater bandwidth (4133 MT/s, as compared with 2666 MT/s in comparable DDR3 configurations) at a lower operating voltage (1.2V vs 1.5/1.65V) and so is more power efficient than the previous standard. This does mean that, in contrast to previous Intel Core generations, new Skylake systems will not be able to inherit DDR3 DIMMs from the older systems they will replace.

Complementing support for DDR4 memory is a substantial revision to how Intel approach overclocking with K-series CPUs. Limited to multiplier adjustments since Sandybridge – a very simple by effective means for everyone to get more out of their CPU – Skylake returns to Base Clock (BCLK) overclocking in a big way. By no longer tying the subsystem clock directly to the BCLK (and hence requiring that it stay fixed) Skylake systems are free to adjust the BCLK in 1ms increments, translating to direct memory overclocks without coarse ratios. Novice overclockers can still go down the route of only adjusting the multiplier, but more adventurous users are now free to tinker to their hearts content.


TDP has risen with Skylake compared to Devil’s Canyon, but only fractionally. It’s likely that most of this is down to the more robust GPU within Skylake compared to the Haswell-era models, but may also indicate other underlying changes which we haven’t been briefed on. The most notable consequence is that the Fully Integrated Voltage Regulator (FIVR) has been removed (citing TDP issues), and once against the platform chipset controls most CPU voltages. A boon for overclockers, we really should make best use of it while it lasts; an FIVR may well once again be implemented in the shrink to 10nm.

Finally, moving to the chipset features, it’s notable that the PCI-Express lanes provided by the PCH have been upgraded to PCI-Express 3.0. The chief cause is new generations of PCI-Express SSD storage that are beginning to saturate two lanes of PCIe 2.0 through either M.2, SATA-Express or direct PCI-Express slot interfaces. Further bolstering the throughput is an upgrade to DMI 3.0 on desktop SKUs of the Skylake platform, a standard which is likely necessary to handle NVMe drives in Raid configurations. Speaking of, many next-generation drives are now RAID-able when used in multiples, depending on the exact level of implementation on the motherboard itself.

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