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Is Intel's Skylake Finally A New CPU To Get Excited About?

It's all-new. Is it any good?

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Hello, good evening and give it up for an all-new Intel CPU. By chip industry standards, it’s been a long time coming. But with a nonchalant shrug of its 14nm FinFETs, Intel’s new Skylake chip has crashed the desktop PC party. Dare we hope for genuine progress? Or is the new Core i7-6700K yet another samey CPU from Intel? I also have an early take on the new Z170 platform that pairs with Skylake, in the form of MSI’s Z170 Gaming M5 motherboard. Without giving much away, Skylake is something we desktop gaming dinosaurs can definitely get excited about. But not necessarily for the reasons you might expect.

Note:
There’s a fair bit to get through this week, so I’ve provided a TL;DR at the bottom for anyone who can’t be bothered.

Skylake, then. It’s actually Intel’s second-generation 14nm processor. That means it’s a ‘tock’ in Intel’s Tick-Tock chip development parlance, and so an all-new design.

The ‘tick’ that begat Skylake’s ‘tock’ in this instance (confused yet? I am) is the blink-and-you’ll-miss-it 14nm Broadwell family. Actually, I did miss it since I’ve not covered the distinctly peculiar Broadwell Core i7-5775C and Core i5-5675C desktop chips. You can read about them here.

The odd back-to-back launches and peculiar specification of those Broadwell chips (they’re expensive, have pointlessly powerful integrated graphics, but as pure CPUs are mostly no faster than previous Intel chips) are down to Intel’s difficulty in getting to grips with its 14nm silicon production tech.

But look on the bright side. Intel could have pushed this new Skylake chip out to later this year, leaving Broadwell some breathing space. Instead, it cooked up some oddball Broadwells to fit into a tiny niche and rolled out Skylake soon after.

Those new CPUs in full

Specifically, there are two new CPUs and a new chipset and socket to go with them. The CPUs are the Core i7-6700K, which I’ve had my hands on, and the cheaper Core i5-6600K, which I haven’t.

This is Skylake.

Spec-wise, we’re talking four cores for each with Hyperthreading and thus support for eight software threads restricted to the i7 model. Yup, that’s exactly the same as we’ve seen for at least the last five years.

Clockspeeds haven’t exactly exploded upwards, either. In fact, the 6700K’s maximum 4.2GHz Turbo speed is actually 200MHz slower than the old Core i7-4790K, from the 22nm Haswell generation. The 6700K’s 4GHz nominal clockspeed is at least a match for the 4790K. But that means a Turbo boost of just 200MHz. What, exactly, is the point?

Whatever, the Core i5-6600K seems to make more sense by both increasing clockspeeds all round with a modest 100MHz over the old Core i5-4670K, and by maintaining 400MHz of Turbo boost with 3.5GHz nominal and 3.9GHz boost clocks. But either way, with no big changes to clockspeeds and no additional cores, the only chance that these chips have of delivering a tangible performance bump is by design improvements to the cores.

You will need a new motherboard, it is the way of things.

Problem is, Intel long ago pinched all the low-hanging fruit when it comes to improving its CPU cores. Then its engineers climbed the higher branches and tore the tree bare. Put simply, its current x86 architecture is ruthlessly optimised and it’s likely that nothing short of a massive and risky design revolution would deliver a big gain.

Long story short, there’s not much in the official documentation about the specifics of any changes to Skylake’s CPU cores for Skylake and, as we’ll see, what changes there are haven’t made a big impact. Ditto the new graphics architecture for Skylake. There is one and it’s in the 6700K, but details beyond a bump to 24 execution units are sparse. In any case, I didn’t try the integrated graphics because it’s bleedin’ integrated graphics, which isn’t something we have to or should resort on a desktop PC.

The new Z170 chipset and LGA1151 socket
At this stage you’ll be wondering what the devil there is to be remotely interested in with Skylake. So here it comes. Firstly, there’s a new platform, chipset and socket. The bad news is that means you can kiss goodbye to backwards compatibility with older motherboards. It’s a goner.

DDR4 is part of the new Skylake package, too.

The new LGA1151 socket only works with Skylake chips, so you’ll need a new motherboard. And some new memory, for now at least. That’s because the first motherboards based on the new Z170 chipset require expensive, relatively new DDR4 memory. However, Skylake’s memory controller is actually compatible with DDR3L (the low-voltage version of DDR3 memory). But we’ll have to wait a while for compatible boards.

Bags of bandwidth for USB devices and SSDs
In the meantime, there are a few other features worth noting when it comes to Skylake motherboards. Our example board in this case is MSI’s Z170 Gaming M5, the entry-level effort in MSI’s enthusiast gamer range and yours for about £150.

Look carefully, and you’ll see a load of bandwidth-friendly features. Firstly, there’s a pair of M.2 ports for super-fast SSDs (see our guide to these here). Sadly, only one of them will run in the faster PCI Express mode at a time, however. With two M.2 drives installed, the other will default down to slower SATA mode.

Your M.2 SSD goes here. You have got an M.2 drive, right? Ah.

Then there’s the back panel. You’ll find no fewer than four different USB ports reside therein. You get a couple of USB 2.0 ports. Then there are four faster USB 3.0 sockets, a feature provided natively by the Z170 chipset.

Next up is a standard Type-A USB 3.1 port that doubles USB 3.0’s bandwidth to 10Gbps. And finally, there’s a USB 3.1 Type-C port which is the teensy little oval-shaped hole that not only offers big bandwidth, but also fully reversible connectivity, just like Apple’s Lightning connector. In other words, it doesn’t matter which way round you stuff the cable in, it just works.

As if that wasn’t confusing enough, for reasons unknown to science most motherboard makers have taken to referring to USB 3.0 as USB 3.1 gen 1, while USB 3.1 proper becomes USB 3.1 gen 2. It’s ridiculous, but now you know.

Just your common-or-garden USB 3.1 gen 2 Type-C port.

Whatever, what’s really critical to understand is that the new Z170 chipset has been upgraded to native PCI Express compatibility with a total of four lanes. To enable these lanes to actually deliver on that performance promise, the speed of the interface between the chipset and the CPU, known as the DMI bus, has been doubled. The Skylake CPU itself still has 16 lanes.

The upshot of all this is that you can connect an M.2 SSD at proper PCI Express 3.0 speeds without pinching lanes from the CPU and in turn from your graphics card.

Old-school overclocking returns

The other big news with Skylake involves overclocking and specifically the freeing up of the baseclock for overclocking as an alternative to the multiplier. In recent years, baseclocks in Intel chips could only be tweaked in big ratio jumps (ie 100MHz then 125MHz and 166MHz) and the result combined with a multiplier-locked CPU was usually a non-bootable system. It wasn’t a terribly relevant tool. Now you overclock in 1MHz intervals.

In my testing, I achieved the same overclock (4.7GHz, for the record) for the 6700K chip using both the baseclock and the mutliplier, the latter being unlocked on the first Skylakes due to their ‘K’ series specification. What’s really interesting, of course, is the prospect of future Skylakes with locked multipliers which in theory should really benefit from the fully accessible baseclock. Could the good old days of clocking the twangers off a cheap Intel chip be back? It seems possible, but I’ll believe it when I actually see it.

This has nothing to do with overclocking, sorry. But get a load of those four different USB port types.

In the meantime, I can confirm that the new 6700K performs almost no differently from the old 4790K. OK, there are a few percentage points here and there in the new CPU’s favour. And the odd synthetic benchmark runs a lot faster, most obviously in memory bandwidth thanks to that DDR4 memory.

But in subjective terms, you wouldn’t feel a thing going from a decent Haswell chip to Skylake. If this launch was just about the 6700K and 6600K CPUs, therefore, it would be a total bust. But the platform tweaks and the added overclocking opportunities make it a lot more interesting than the last couple of Intel refreshes, mercifully.

More about Z170 motherboards
On a final point of order, it’s worth noting one further change. Intel has removed the CPU voltage regulator from the chip, which means it’s now back on the motherboard. The reason is to do with managing thermals, but the important point is that it makes motherboard component quality more critical for overclocking.

Well, that’s the theory. I’ve tested four different motherboards, including the MSI’s big Gaming M7 brother and a couple of cheap Asus boards, the Asus Z170-A and the Z170 Pro Gaming. Every single one achieved the same 4.7GHz maximum overclock with my particular 6700K sample. The only deviation involved the Asus Z170 Pro Gaming, which achieved the same 4.7GHz baseclock result in theory, but when actually in Windows tended to clock down under load. It was fine when overclocking via the multiplier. Is this a harbinger of things to come with cheaper Z170 boards? Possibly.

An entry-level enthusiast board like the MSI Z170 Gaming M5 is probably the sweet spot for Skylake mobos.

All of which means you’ll probably need to be that little bit more careful when choosing a motherboard for overclocking future cheap Skylake. But if the MSI Gaming M5 is anything to go by, you won’t need an absolutely bleeding edge board. Something in the middle market with just a little more attention paid to component quality will do.

TL;DR
– Intel has launched two new 14nm Skylake CPUs, the Core i5-6600K and the Core i7-6700K.

– There’s a new Z170 chipset and a new socket, too, so you’ll need a new motherboard.

– For early motherboards, you’ll need some new DDR4 memory, too.

– Performance of the new CPUs is completely uninteresting.

– However, the new Z170 platform has lots of lovely bandwidth with added support for fast PCI Express SSDs and USB 3.0

– The new platform now allows for overclocking CPUs via the baseclock, which could prove very interesting when cheaper Skylake CPUs with locked multipliers are released.

– Intel has also moved the CPU voltage regulator onto to the motherboard, which makes motherboard quality more critical for overclocking.

– Finally, watch out for Z170 motherboard makers using ‘USB 3.1 gen 1’ to mean USB 3.0 and ‘USB 3.1 gen 2’ to mean USB 3.1.

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Jeremy Laird

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