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

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:

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:

Continue to page 2 for the benchmark charts.