Intel Skylake review: An upgrade well worth making

Darien Graham-Smith September 11, 2015

Just as we were getting to know Intel’s Broadwell CPUs, their successors have arrived: the sixth-generation Skylake range. The rapid turnaround is down to delays in the release of Broadwell, which saw the 14nm chips hit mass production a year later than planned. Now that the 14nm process is up and running, a quick switch to the new Skylake architecture puts the company back on schedule – for now anyway.

Intel Skylake review: An upgrade well worth making

Skylake’s new features include an improved branch predictor and larger buffers for out of order execution; in practical terms, that means the CPU spends less time waiting for data and instructions, improving overall performance. Skylake also introduces a new system called Speed Shift, which lets the CPU manage its own power state, rather than following the operating system’s lead, enabling it to match demand more precisely. The overall effect is a respectable performance boost: the first Skylake desktop chip, the Core i56600K, proved 17% faster in our desktop-based image-editing benchmark than the Haswell-based Core i54670K.

Of course, the CPU core is only half the story. The new HD Graphics 500series GPU brings support for DirectX 12, OpenCL 2 and OpenGL 4.4, with claimed performance benefits of 20-40% over last-generation silicon. That’s borne out by our experience: in High quality mode at 720p, we saw average frame rates in Dirt: Showdown leap from 32fps on the Core i54670K to 45fps on the new Skylake chip.

Also of interest are new hardware functions: a dedicated H.264 encoder can drive wireless displays without taxing the general-purpose graphics hardware, and there’s support for the more efficient H.265 codec too. Photographers will be pleased to learn that Skylake also introduces new hardware features aimed specifically at processing raw camera images.

The third leg of the stool is the chipset, which introduces support for superfast DDR4 memory – although compatibility with DDR3 remains too. A new webcam controller promises “zero shutter lag” on sensors up to 13 megapixels, plus features such as burst mode and face detection.

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Other onboard controllers include SATA Express and Thunderbolt 3 – capable of running at 40Gbits/sec over a USB Type-C port. While it doesn’t appear to be mandatory, Intel is also pushing WiGig alongside Skylake, to allow all sorts of peripherals to be connected wirelessly.

Prior to the launch, it was rumoured that wireless charging would be included too, but Intel has remained quiet on that idea this time around.

The first two Skylake CPUs – the 4GHz Core i76700K and 3.5GHz Core i56600K – are on sale now. Both are desktop chips aimed at the high-performance end of the market, but they’ll soon be joined by a full range of Core i3, i5 and i7 parts, in both desktop and mobile forms. Specifics are yet to emerge, but similar to Haswell the family will be divided into Y, U, H and S classes, with TDPs ranging from 4W to 91W. They’ll also be joined by new low-power Core M parts – now ranged into Core m3, m5 and m7 models, to support both dirt-cheap devices such as Intel’s Compute Stick and ultraportables such as the Apple MacBook.

Later this year, we can also expect vPro variants, plus Skylake Celeron and Pentium chips for the budget market – while those seeking higher performance may be tempted by new quad-core and unlocked mobile parts. The first mobile Xeon is on its way too, along with new Iris and Iris Pro GPUs.

We encountered our first Skylake processor at the start of August in a desktop PC. The unlocked Core i56600K, overclocked to a maximum of 4.34GHz, helped that system achieve a stupendous overall benchmark score of 137. At its stock frequency, our test system scored 113 overall, versus the 100 achieved by our Haswell based reference system.

What that says about the platform as a whole remains to be seen. Some Skylake chips will have large caches, HyperThreading and generous Turbo Boost capabilities, while others will focus on minimising size, heat and power consumption. All things being equal, however, any Skylake chip should comfortably outpace a comparable Broadwell CPU, and will benefit from new GPU and chipset features too. It’s an upgrade that’s well worth the surprisingly short wait.

Introducing Kaby Lake

According to Intel’s original “Tick-Tock” timetable, Skylake was supposed to be followed next year by a shrink to 10nm, dubbed Cannonlake. But after the delays that beset Broadwell’s move to 14nm, Intel has wisely tweaked its roadmap to defer Cannonlake until 2017.

Instead it now plans to introduce an interim 14nm architecture, codenamed Kaby Lake, next year. That may be preferable to two years of stagnation, but it’s a very short development period for a new CPU. We’ll be watching with interest to see what improvements Intel manages to work into the new design.