The Intel 6th Gen Skylake Review: Core i7-6700K and i5-6600K Tested
by Ian Cutress on August 5, 2015 8:00 AM ESTIt’s the Intel review you’ve been waiting for. Today is the launch of the first two CPUs from Intel’s Skylake architecture, the 6th Generation Core i7-6700K and the Core i5-6600K. With the new processors we get a new architecture, a new socket, the move to DDR4 and the potential to increase both performance and efficiency at the same time. A lot of readers have asked the question – is it time to upgrade? We had a CPU or two in to test to answer that question.
Launch Day for Skylake-K: August 5th
For those in the industry, predicting Skylake’s launch has been a minefield. Even at Computex in June, some companies were discussing a large six-week window in which they expected Skylake but were waiting on official dates. But as we've seen with a number of previous Intel mainstream launches, Intel likes to aim at the gaming crowds release at a gaming events. It just so happens that today is Gamescom in Germany, two weeks before what everyone expected would be a launch at Intel’s Developer Forum in mid-August.
Today is a full launch for the Skylake-K processors, with the two CPUs being launched alongside new Z170 series motherboards and dual channel DDR4 memory kits. Having spoken to a few retailers, they have stock ready to go today. That being said, a number of them would have liked more stock on launch day, suggesting that they expect the processors to sell out rather quickly when the buy buttons are activated.
All the motherboard manufacturers should be ready to go as well – take a look at our breakdown of the retail motherboard information we could get before launch for a good overview of what to expect this generation. DDR4 manufacturers have been selling the new standard of memory for over a year due to Intel’s high-end X99 platform supporting it, but today will see the introduction of dual channel kits to go with the Skylake platform as well as a number of higher speed modules ready and waiting.
‘Where are the non-K processors?!’ you may ask. Intel tells us that these will be released later in the year, sometime in Q3. As a result, we have to wait and see what range of models come out at that point and we will get a number in to review.
Retail Packaging
To go with the launch is a new look of Intel's Core processor packaging, in part to appeal to the gaming crowd. As the gaming industry is considered one of the few remaining areas for potentially large growth in the PC industry, Intel is increasing its focus on gaming as a result.
Aside from changing the graphics on the box, it has been reported – and seemingly confirmed by the thinner boxes in the official pictures from Intel – that these processors will not be shipped with a stock Intel cooler. Users will have to purchase third party coolers. Part of this makes sense – overclocking processors need beefier cooling in order to extract the maximum overclock and buying something above the stock cooler should be good. The downside of not having a stock cooler means an added cost to the end user. However as the hole mounting for the new socket, LGA1151, is similar to that of LGA1150/1155/1156 – spacing is still 75mm – many existing CPU coolers for the current LGA115x sockets should be compatible, making it possible to reuse many coolers for no more than the cost of a new thermal paste application.
For users looking for a new air or liquid cooler, head on over to our recent roundup of Top Tier CPU Air Coolers Q3 2015: 9-Way Roundup Review and the Closed Loop AIO Liquid Coolers: 14-way Mega Roundup Review published last year.
The Skylake CPUs: Intel’s 6th Generation Core
Intel’s tick-tock strategy has been the bedrock of their application to bring new processors to the market, growing in terms of user experience for either power, efficiency, or both. It has been noted that certain generations either have an enterprise focus or a mobile-first focus, which always seems to tip the scales in one direction of the other. However, with the recent announcement of a third CPU line at 14nm called Kaby Lake for 2016, tick-tock just became tick-tock-tock.
Intel's Tick-Tock Cadence | |||||
Microarchitecture | Process Node | Tick or Tock | Release Year | ||
Conroe/Merom | 65nm | Tock | 2006 | ||
Penryn | 45nm | Tick | 2007 | ||
Nehalem | 45nm | Tock | 2008 | ||
Westmere | 32nm | Tick | 2010 | ||
Sandy Bridge | 32nm | Tock | 2011 | ||
Ivy Bridge | 22nm | Tick | 2012 | ||
Haswell | 22nm | Tock | 2013 | ||
Broadwell | 14nm | Tick | 2014 | ||
Skylake | 14nm | Tock | 2015 | ||
Kaby Lake (link)? | 14nm | Tock | 2016 ? |
Intel’s early issues with 14nm yields have been well documented and we won’t go into them here, but 14nm is a more expensive process with an increased number of lithography steps as we reach the limits of current semiconductor technology. FinFET was introduced back in 22nm, but to move down to 10nm makes either the current process more expensive or other methods have to be used. As a result, we see Moore’s Law stretching out from an 18-24 month cadence to a 24-30 month cadence for the first time in fifty years. As we’ve seen with the graphics card market recently stalling at 28nm, there is a need (or at least opportunity) to develop more power efficient architectures rather than just relying on die shrinks to do it for you.
Future development aside, today Skylake will hit the shelves in the form of two overclockable processors, the Core i7-6700K and the Core i5-6600K.
Intel i7 Lineup | |||
i7-4770K | i7-5775C | i7-6700K | |
Price | $339 | $366 | $350 |
Cores | 4 | 4 | 4 |
Threads | 8 | 8 | 8 |
Base CPU Freq. | 3.5 GHz | 3.3 GHz | 4.0 GHz |
Turbo CPU Freq. | 3.9 GHz | 3.7 GHz | 4.2 GHz |
Graphics | HD 4600 (GT2) | Iris Pro 6200 (GT3e) | HD 530 (GT2) |
EUs | 20 | 48 | 24 |
iGPU Freq. | 1250MHz | 1100MHz | 1150MHz |
TDP | 84W | 65W | 91W |
DDR3/L Freq. | 1600MHz | 1600MHz | 1600MHz |
DDR4 Freq. | - | - | 2133MHz |
L3 Cache | 8MB | 6MB | 8MB |
L4 Cache | None | 128MB (Crystal Well) | None |
Interface | LGA1150 | LGA1150 | LGA1151 |
As with previous nomenclature, the i7 model will be quad core CPU with HyperThreading and 8MB of L3 cache. This matches up with the Haswell parts to which Skylake is more closely aligned (Desktop Broadwell is rather a blip, using an external on-package eDRAM and you can read our review here), in a large number of aspects including the other cache levels. The 6700K runs at a base frequency of 4.0 GHz and an all-core frequency of 4.2 GHz. This is a slight speed bump over the 4770K which was launched at the start of Haswell, but a minor reduction in clockspeeds compared to the i7-4790K, which was an upgraded Haswell part launched later under the name of ‘Devil’s Canyon’.
The integrated graphics nomenclature has changed, with the new i7-6700K having the Intel HD 530 graphics, compared to the HD4600 in the Haswell parts. We know that the HD 530, like the HD 4600, has 24 of Intel’s execution units in the iGPU, and they run at a peak frequency of 1150 MHz. The introduction of the HD 530 marks the launch of Intel’s 9th generation graphics, and we'll cover Gen9 in a bit more detail later.
Intel i5 Lineup | |||
i5-4670K | i5-5675C | i5-6600K | |
Price | $242 | $276 | $243 |
Cores | 4 | 4 | 4 |
Threads | 4 | 4 | 4 |
Base CPU Freq. | 3.4 GHz | 3.1 GHz | 3.5 GHz |
Turbo CPU Freq. | 3.8 GHz | 3.6 GHz | 3.9 GHz |
Graphics | HD 4600 (GT2) | Iris Pro 6200 (GT3e) | HD 530 (GT2) |
EUs | 20 | 48 | 24 |
iGPU Freq. | 1200MHz | 1100MHz | 1150MHz ? |
TDP | 84W | 65W | 91W |
DDR3/L Freq. | 1600MHz | 1600MHz | 1600MHz |
DDR4 Freq. | - | - | 2133MHz |
L3 Cache | 6MB | 4MB | 6MB |
L4 Cache | None | 128MB (Crystal Well) | None |
Interface | LGA1150 | LGA1150 | LGA1151 |
The i5 model for Skylake also has quad cores, but without HyperThreading and only 6MB of L3 cache. Like the i7, it also has the Intel HD 530 graphics but operates at a lower frequency band.
Both the Skylake processors will support DDR4 and DDR3L memory in order to ease the transition to DDR4 for the mainstream segment, although it should be said that DDR3L is implemented here due to its lower than standard DDR3 operating voltage of 1.35 volts. This more closely aligns with DDR4’s standard voltage of 1.20 volts or the high end DDR4 kits at 1.35 volts, and as a result we are told that motherboards that support DDR3L will typically only be qualified to run DDR3L kits, rather than DDR3 kits.
This leads onto the point that both of the K processors for Skylake sit at 91W, which is a small increase over Haswell at 84W and Devil’s Canyon at 88W. In the past Intel has historically run a 1:1 policy whereby a 1% performance gain must come at a maximum of a 1% power penalty – this was adjust to 2:1 for Broadwell, and we should assume that Skylake had similar requirements during the planning stage. Depending on the specific architecture details, one potential source for this increase in power consumption may be the dual memory controller design, although Skylake has a significant number of features to differentiate itself from Haswell.
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mkozakewich - Thursday, August 6, 2015 - link
It's unlikely you'll be seeing doubles and doubles anymore. If you look at what's been going on for the past several years, we're moving to more efficient processes instead of improving performance. I'm sure Intel's end goal is to make powerful CPUs for devices that fit into people's pockets. At that point you might see more start going into raw performance.edlee - Wednesday, August 5, 2015 - link
i am not sure why conclusion to the review makes it seem i7-2600k users should upgrade to this.If you are a gamer, there is no 25% improvement in average or minimum frame rate, its 3-6% at best.
Is this the future of intel's tock strategy, to give very little improvement to gamers?
VeauX - Wednesday, August 5, 2015 - link
On the gaming side, you'll never see a speed bump if you are not CPU Limited. Once you have a decent CPU, just put your money in GPU, period.Nagorak - Wednesday, August 5, 2015 - link
CPU is almost irrelevant for games at this point. As games start to take advantage of more cores, older processors are utilized more efficiently, further negating the need to upgrade. DX12 may improve this further.I sort of wonder if Intel isn't on a path to some trouble here. There's basically no point for anyone to upgrade their CPU anymore, not even gamers. Other than a few specialized applications the increase in performance just doesn't really matter, if it exists at all.
AndrewJacksonZA - Thursday, August 6, 2015 - link
I also sometimes think that, but then I remember that we developers *WILL* find a way to make use of more computing power.Having said that, I still can't quite justify me upgrading from my E6750 and 6670 @ 1240 x 1024. I slapped in an SSD in February last year and it was like I got a brand new machine.
Chrome and Edge on Win10 lag a teeny tiny bit though, maybe I can use that as my justification... Perhaps a 5960X or a 5930K though - more cores FTW? Or perhaps a 6700K and get it to 5GHz for the rights to claim some "5GHz Daily Driver" epeen... ;-)
Zoomer - Friday, August 14, 2015 - link
Exactly, I reached the opposite conclusion as Ian. There is no point in upgrading even from SB. If you do, stick to DDR3. Only GTA5 benefits from DDR4.It's interesting to see if regular DDR3 sticks can run on Skylake, perhaps by bumping the Vsa, voltages. Not clear if Ian's overclocking tests were with the IGP disabled - would be interesting to see if disabling the IGP / reducing Fgt, Vgt helps overclocking any.
StevoLincolnite - Wednesday, August 5, 2015 - link
I'm still happily sitting with my Sandy-Bridge-E. Still handles everything you could throw at it just fine... And still gives Intel's $1,000 chips a run for their money whilst sitting at 5Ghz.mapesdhs - Wednesday, August 12, 2015 - link
Yup, that's why my most recent gaming build was a R4E & 3930K, cost less than a new HW build, much quicker overall. My existing SB gaming PC is 5GHz aswell (every 2700K I've tried handles 5.0 just fine).leexgx - Monday, August 10, 2015 - link
hmm maybe i can upgrade from my i7-920 now (really any of the newer intel cpus are faster then it)sheeple - Thursday, October 15, 2015 - link
DON'T BE STUPID SHEEPLE!!! NEW DOES NOT ALWAYS = BETTER!