Intel Skylake: Intel Z170 Chipset and Core i7-6700K Review

Performance Analysis

What to make of Skylake, then? In many ways, it's much the same as we've seen of late - an incremental increase in performance that has more of an impact outside of games. There are noticeable increases in video editing and photo editing performance and even larger speed boosts in rendering as the Terragen 3 and Cinebench R15 tests show. We wanted to focus on comparable Intel mainstream CPUs but as the Intel Core i7-5820K costs about the same, we also introduced this to the 2D tests. Interestingly, the LGA2011-v3 CPU doesn't hold much of an advantage over the Core i7-6700K and was far less overclockable too. However, for rendering it can easily outperform it thanks to its extra cores, so if this is something you do a lot of, X99 rather than Z170 is the way to go. Interestingly, in the video editing test, the Core i7-6700K had the advantage both at stock speed and overclocked so in cases where the Core i7-5820K's additional threads don't count for much, the extra grunt afforded by the Core i7-6700K's higher frequency comes into play.

Gaming is always a tricky question to answer. Our selected games have shown the biggest differences in terms of CPU performance scaling out of a dozen or so that we've tested so while Bioshock Infinite is fairly old, we included it to represent games both new and old that respond to a little extra CPU grunt. The fact of the matter is with a single high end graphics card, the GPU itself is likely to be the main bottleneck, even at 1,920 x 1,080. Only when you drop another GPU into the mix do you see a little more dependence on the CPU, as we've seen with our X99 benchmarks. As single GPUs are going to be by far the most likely option for Skylake system owners, we felt it right to use a single GPU for game testing rather than throw another in just for the sake of seeing larger differences in games.


That said, there were benefits in the 3D tests. The move from a Core i7-4770K to a Core i7-6770K saw over 100 points added to the Unigine Valley score, 4fps added to the minimum frame rate in Alien: Isolation and a slight bump in Bioshock Infinite too. However, these results obviously don't warrant an upgrade. We'd likely have seen more of a difference in games such as The Elder Scrolls V: Skyrim, which scaled quite well with CPUs but as a four year-old game, we didn't think it warranted a place in the line-up. Likewise, we saw next to no difference in Crysis 3, Battlefield 4 or GTA V, which is why they're absent from the graphs.

Looking past the last three generations (four if you include Broadwell which is sadly absent from the graphs as we're yet to obtain a sample), the answer to the question of whether you should upgrade is clear - yes. Sandy Bridge has been outdone in every test and in many cases by significant margins and even hefty overclocks can't help in some situations. However, in games, the difference isn't huge - it's photo/video editing and rendering where the real performance increases creep in.

Power-wise, a direct comparison isn't possible due to the variation in hardware, both between the Z170, Z97 and Z77 motherboards we used and the fact that you've got DDR3 and DDR4 in the mix as well. In terms of TDP, there's very little in it, and our benchmarks appear to confirm that too.

Overclocking

While there's a whole baseclock range to play with, due to time constraints we've only played with the multiplier, but for the most part, this is all you'll likely need for a decent overclock anyway, especially as simply raising the baseclock doesn't yield much of a performance increase on its own.

We were initially pretty impressed with the results from our sample - 5GHz seemed to be achievable on a modest all-in-one liquid cooler using 1.37V, which saw the temperatures hover around the high eighties. However, while it was Prime95 stable and ran through most of our benchmarks, Terragen 3 kept crashing.

In the end we had to knock things back to 4.8GHz to get perfect stability, and this also allowed us to reduce the vcore to 1.35V - still more than we'd generally need to overclock a Devil's Canyon or Haswell CPU to the same frequency, although all CPUs are different of course. Still, with watercooling, 5GHz+ is likely on the cards if you get a good sample.

Conclusion

While Skylake is perhaps just another incremental speed increase in terms of CPU performance - something that we've all been getting a little tired of since Sandy Bridge, the extra features offered by the Z170 chipset and the package as a whole make Skylake a tempting proposition and we felt it important to factor this into the scores as well, rather than just focussing on the CPU. This is especially so if you've been drooling over an X99 setup but can't justify the cost. That said, the Core i7-6700K retails for close to the same price as the Core i7-5820K - a CPU with two additional cores and four additional threads, while X99 motherboards retail for not much more than premium Z170 boards too - the Asus Z170-Deluxe for example retails for £225 and we've seen several good X99 boards come in at less than that. The Core i7-6700K is at a sizeable disadvantage in rendering too, where the Core i7-5820K's extra threads came into play. Outside of this and considering the 28-lane PCI-E limitation of the Core i7-5820K compared to its 40-lane siblings, though, the Core i7-6700K is arguably the better bet.

In addition, the Z170-Deluxe is Asus' top-end non-ROG board - the Z170-Pro Gaming costs a little over £100 so combined with the fact that you'll only need a dual-channel DDR4 kit, there's still the ability to save a fair amount by opting for Skylake. You can drop two high end GPUs into the mix and not see any bottlenecks as well - a x8/x8 lane configuration is more than up to the task of dealing with two GTX 970s. The main reason for opting for X99 has been better multi-GPU and next-gen storage support, but Z170 makes obtaining the latter more affordable - the financial lines between Z170 and X99 are certainly more fuzzy than they were with Z97 and X99 though.

As for the CPUs themselves, the high launch prices will likely put many off - £290 is a lot for a mainstream CPU and the Core i5 isn't much better. As we said earlier in the review though, this isn't the kind of launch where we'd expect to see high adoption rates. You have a new CPU socket and new memory so prices will be high to make the most of the inevitable early adopters. DDR3 has been around for what seems like an age so having to do the full upgrade probably feels quite unfamiliar too. Prices will come down, but for the moment Skylake is reserved for those in desperate need for a new system or upgrade, especially if that involves some sort of next-gen storage. Likewise, unless you're on a very tight budget, there's also very little point not opting for an LGA1151-basesd system seeing as LGA1150 has finally come to the end of its life.