Intel Core i7-6700K Skylake CPU Review & Gaming Benchmarks

By Published August 05, 2015 at 8:40 am

Additional Info

  • Component: CPU
  • Original MSRP: 350
  • Manufacturer: Intel

Today marks the public release of Intel's codename “Skylake-S” platform, a new 14nm microarchitecture designated for use in the company's newest line of CPUs. The Core series CPUs see accompaniment from a new Z170 chipset, found on each of the motherboards included in our Skylake Z170 board round-up. Skylake is targeted heavily at the PC gaming userbase, which is currently experiencing a heavy surge in platform adoption.

Intel's platform flagship is the i7-6700K ($350), sticking to the well-known 4-core, 8-thread approach by way of matured hyperthreading technology. Prior to Skylake, Intel shipped its Devil's Canyon update to Haswell, a worthwhile, same-price replacement with slightly bolstered clockrates. The “Haswell Refresh” CPUs have been mostly forgotten at this point, but were released in close proximity to Devil's Canyon. This string of same-generation releases is uncharacteristic of Intel, who generally launch the mainstay i7 and i5 for each architecture before immediately shifting gears to the next platform release.

The i7-6700K effectively replaces the i7-4790K (2014) in the stack, which replaced the i7-4770K (2Q13). The i5-6600K ($240) replaces the i5-4690K, which replaced the i5-4670K before it. The Skylake branding makes a return to what is more familiarized from Sandy Bridge, dropping the XX7X identifier.

We're going to be publishing various components of this CPU review in bursted increments. Our objective is to explore several individual facets in more depth (as it relates to video graphics, especially), and that will require more time than we were given before launch. This review is an initial analysis of hard gaming performance. Overclocking, power, thermals, PCI-e lane scalability, and more are forthcoming.

Today, we're reviewing Intel's Skylake i7-6700K CPU on the Z170 chipset; we've dedicated all of our efforts to gaming benchmarks to analyze FPS gain using the i7-6700K. The new CPU was pitted against other Intel models of recent years, including the 4770K, 4790K, and i5- models 4690K and 3570K. Production workload tests will be performed separately from this initial review and will release in the future. Our focus today is entirely on gaming and overclocking.

Intel Core i7-6700K & i5-6600K CPU Specs

  i5-4670K i5-6600K i7-4770K i7-6700K
Cores 4C/4T 4C/4T 4C/8T 4C/8T
Frequency 3.4GHz /
3.8GHz T
3.5GHz /
3.9GHz T
3.5GHz /
3.9GHz T
4.0GHz /
4.2GHz T
EUs 20 24 20 24
IGP HD4600 HD 530 HD4600 HD 530
IGP Frequency 1200MHz 1150MHz 1250MHz 1150MHz
TDP 84W 91W 84W 91W
Cache 6MB L3
0MB L4
6MB L3
0MB L4
DRAM Frequency 1600MHz DDR3L 1600MHz DDR3L
2133MHz DDR4
1600MHz DDR3L 1600MHz DDR3L
2133MHz DDR4
Socket LGA1150 LGA1151 LGA1150 LGA1151
Cost $240 $240 $340 $350

DDR4 feels a little “stale” given its X99 launch but, for the mass consumer market, Skylake will be the first time that DDR4 lands on the buying list. Skylake is technically capable of supporting both DDR4 and DDR3L (2133MHz and 1600MHz natively, respectively), but all gaming-grade boards we've got access to host DDR4 slots.

DDR4 is still expensive. It'll come down as the market undergoes a massive switch-over, something we've already forecast for 2016. The added cost of DDR4 inflates overall system build cost in a sort of “hidden” fashion at this point.

Intel's i7-6700K and i5-6600K are equipped with the new HD 530 IGP, something we omitted from testing due to unavailability of the driver in time for launch.

The Z170 Chipset Architecture vs. Z97



Above is the new block diagram for Intel's Z170 chipset, its latest performance-series brain stem. The existing Z87 / Z97 chipset is also on display.

The biggest and most immediate gain from Z170 is its additional lane availability. Z97 coupled with a Haswell processor yields a combined 24 PCI-e lanes (a mix of 2.x and 3.0), something that constricts options when dealing with multi-GPU and modern SSD configurations. A single GPU instantly consumed 16 lanes – whether or not it measurably benefits from the full allocation – and M.2 SSDs will use another 4 lanes. Multi-GPU + M.2 / NVME configurations instantly saturate the entirety of the PCI-e controllers.

Skylake itself still hosts the same lane count on the new i7 and i5 flagships as Haswell, but increases the chipset's availability to 20 lanes. The total PCI-e lane availability with this configuration now rests at 36, a big enough gain to allow full dual x16 GPU configurations with an SSD routed through the PCI-e bus.

Intel is looking out for its own interests, here: Its 750 Series SSDs use PCI-e lanes on the motherboard to gain the tremendous speed output, something also true of the HyperX Predator SSD and any other M.2 or PCI-e SSDs on the market. Progress is always good, but this is also a strategic move to prepare the market for ultra fast SSD consumption.

A less interesting footnote, the Z170 chipset also bolsters USB3.0 support to 10 ports natively (from 6 on Z87).

Test Methodology

iBUYPOWER provided a complete Skylake system for review on loan.

We tested using our updated 2015 GPU test bench, detailed in the table below. Our thanks to supporting hardware vendors for supplying some of the test components.

The latest AMD Catalyst drivers (15.7.1) were used for testing. NVidia's 353.62 drivers were used for testing. Game settings were manually controlled for the DUT.

Testing was focused on CPU bottleneck analysis. To test at what point the CPU bottlenecks a high-end GPU, we equipped all platforms with a GTX 980 Ti and performed tests using the following settings:

  • Metro: Last Light - Very High w/ high tessellation.
  • GRID: Autosport - Ultra, 4xMSAA.
  • Shadow of Mordor - Ultra preset.
  • GTA V - Very High / High.
  • GTA V - Very High / High with Advanced Graphics (to find bottlenecks).
  • Witcher 3 - Ultra, with SSAO, HairWorks off, and AA off.
  • FireStrike (normal).

All tests had the resolution set to 1080p.

Each game was tested for 30 seconds in an identical scenario, then repeated three times for parity.

Average FPS, 1% low, and 0.1% low times are measured. We do not measure maximum or minimum FPS results as we consider these numbers to be pure outliers. Instead, we take an average of the lowest 1% of results (1% low) to show real-world, noticeable dips; we then take an average of the lowest 0.1% of results for severe spikes. Anti-Aliasing was disabled in all tests except GRID: Autosport, which looks significantly better with its default 4xMSAA. HairWorks was disabled where prevalent. Manufacturer-specific technologies were used when present (CHS, PCSS).

Here is the Intel test bench:

GN Test Bench 2015 Name Courtesy Of Cost
Video Card

GTX 980 Ti

CPU Intel i7-4790K CPU
Intel i5-4690K CPU
Intel i3-4160 CPU
Intel G3258 CPU
Memory 16GB 2133MHz HyperX Savage RAM Kingston Tech. $300
Motherboard Gigabyte Z97X Gaming G1 GamersNexus $285
Power Supply NZXT 1200W HALE90 V2 NZXT $300
SSD HyperX Predator PCI-e SSD Kingston Tech. TBD
Case Top Deck Tech Station GamersNexus $250
CPU Cooler Be Quiet! Dark Rock 3 Be Quiet! ~$60

The Skylake bench made the following exceptions to the above:

  • Intel Core i7-6700K CPU
  • 16GB 2133MHz G.Skill DDR4 Memory
  • ASRock Z170 Fatal1ty Gaming K6 motherboard

And the AMD bench:

GN Test Bench 2015 Name Courtesy Of Cost
Video Card

GTX 980 Ti

CPU AMD A10-7870K
AMD Athlon X4 760K
Memory 16GB 2133MHz HyperX Savage RAM Kingston Tech. -
Motherboard ASUS A88X-PRO GamersNexus $285
Power Supply NZXT 1200W HALE90 V2 NZXT $300
SSD HyperX Savage SSD Kingston Tech. TBD
Case Top Deck Tech Station GamersNexus $250
CPU Cooler Be Quiet! Dark Rock 3 Be Quiet! ~$60

Continue to page 2 for the benchmark charts.

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Last modified on August 06, 2015 at 8:40 am
Steve Burke

Steve started GamersNexus back when it was just a cool name, and now it's grown into an expansive website with an overwhelming amount of features. He recalls his first difficult decision with GN's direction: "I didn't know whether or not I wanted 'Gamers' to have a possessive apostrophe -- I mean, grammatically it should, but I didn't like it in the name. It was ugly. I also had people who were typing apostrophes into the address bar - sigh. It made sense to just leave it as 'Gamers.'"

First world problems, Steve. First world problems.

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