The Intel 6th Gen Skylake Review: Core i7-6700K and i5-6600K Tested
by Ian Cutress on August 5, 2015 8:00 AM ESTIntel’s 6th Gen Skylake Conclusions
The new 6th Generation Skylake platform from Intel has launched today, and as part of the package there are two new processors, the Core i7-6700K and the Core i5-6600K, a new Z170 motherboard chipset with corresponding motherboards, and also a new market for DDR4 DRAM. The purpose of the Skylake platform launch is to update the mainstream PC market segment for the purposes of better performance and enhanced connectivity.
What is Skylake?
Skylake is a new processor architecture based on Intel’s 14nm process using the newest generation of their FinFET lithographic technology, and the two overclockable K series CPUs are the first processors to be released into the wild. For some this is mildly confusing, given that Intel launched Broadwell for desktop (a die shrink "tick" from 22nm to 14nm) only a couple of months ago. Broadwell has only acted as a minor stopgap measure, fulfilling the requirements of an upgradable platform and taking the crown of the best integrated graphics processor for a socket. As a result of that minor role, a number of users will see Skylake more as an upgrade from Haswell, the last mainstream processor family that had a long market shelf life.
For this launch and review, details about Skylake have been relatively rare to come by even in Intel’s own press documents, and we are set to hear more details at Intel’s Developer Forum in mid-August. Nonetheless, we have been able to determine that Skylake has a raft of updates, focusing on fixed function hardware to accelerate certain workloads as well as decoupling the CPU and PCIe frequency domains on the silicon to allow for more precise overclocking.
The platform changes as well. The voltage regulators inside Haswell CPUs move back out on to the motherboard as they generated too much heat inside the CPU. This is good for overclockers, but means the required components on Z170 motherboards, and price, has the potential to go up. The Z170 chipset is the sole chipset being released today, with others coming later in the year. Z170 features an upgrade to DMI 3.0, giving faster CPU-to-chipset bandwidth and enabling a 26-lane high speed IO hub. Of these lanes, 20 can be configured for PCIe lanes under a strict set of rules, giving access to the potential for more functionality on board. Most motherboards being launched today will use these lanes to provide M.2 slots, USB 3.1 Gen 2 ports via controllers, extra networking, extra PCIe slots and SATA Express connectivity. In our motherboard overview we have details on over 55 motherboards to look through.
The Results
Overall, Skylake is not an earth shattering leap in performance. In our IPC testing, with CPUs at 3 GHz, we saw a 5.7% increase in performance over a Haswell processor at the same clockspeed and ~ 25% gains over Sandy Bridge. That 5.7% value masks the fact that between Haswell and Skylake, we have Broadwell, marking a 5.7% increase for a two generation gap.
In our discrete gaming benchmarks, at 3GHz Skylake actually performs worse than Haswell at an equivalent clockspeed, giving up an average of 1.3% performance. We don’t have much from Intel as to analyze the architecture to see why this happens, and it is pretty arguable that it is noticeable, but it is there. Hopefully this is just a teething issue with the new platform.
When we ratchet the CPUs back up to their regular, stock clockspeeds, we see a gap worth discussing. Overall at stock, the i7-6700K is an average 37% faster than Sandy Bridge in CPU benchmarks, 19% faster than the i7-4770K, and 5% faster than the Devil’s Canyon based i7-4790K. Certain benchmarks like HandBrake, Hybrid x265, and Google Octane get substantially bigger gains, suggesting that Skylake’s strengths may lie in fixed function hardware under the hood.
In full speed gaming benchmarks we have some situations that benefit from Skylake (GRID on high end graphics cards) and others that drop (Mordor on GTX 770), but the important aspect to consider is despite Skylake supporting both DDR3L and DDR4 memory, our results show that even with a fast DDR3 kit, a default-speed DDR4 set of memory is still worth upgrading to. On average there’s a small change in performance in favor of the DDR4 (especially in integrated graphics), but DDR4 confers benefits such as more memory per module and lower voltages to aid power consumption
A quick turn to the overclocking situation on Skylake: from our small sample set, most of the CPUs achieved 4.6 GHz when pushing and 4.5 GHz comfortably, including the retail sample that had 4.5 GHz. Speaking to other reviewers, their results match us or even slightly better our own, with one report of a 5.0 GHz gem of a processor. From our testing, Skylake seems to have more of a temperature barrier than a voltage barrier, so increasing the cooling seems to be the task of the day here to get the high frequencies.
With all that, I’m going to make a bold statement.
Sandy Bridge, Your Time Is Up.
A large number of users invested into Intel based platforms during the Core 2 Quad, Nehalem and Sandy Bridge releases. Sandy Bridge was notable because it inferred a large performance gain at stock speeds, and with a good processor anyone could reach 4.7 GHz and even higher using a good high end cooler. With that, Intel has had a problem enticing these users to upgrade because their performance has been constantly matched by Ivy Bridge, Haswell and Broadwell – for every 5% IPC increase from the CPU, an average 200 MHz was lost on the good overclock and they would have to find a good overclocking CPU again. There was no great reason, apart from chipset functionality to upgrade.
That changes with Skylake.
From a clock-to-clock performance perspective, Skylake gives an average ~25% better performance in CPU based benchmarks, and when running both generations of processors at their stock speeds that increase jumps up to 37%. In specific tests, it is even higher. When you scale up to a 4.5 GHz Skylake against a 4.7 GHz Sandy Bridge, the 4% frequency difference is only a tiny portion of that. There are other added benefits, such as the move to a DDR4 memory topology that has denser memory modules, as well as PCIe storage and even PCIe 3.0 graphics connectivity.
As I said above, Skylake is not necessarily the most ground breaking architecture over Haswell. It affords a 19% CPU performance gain over the i7-4770K and 5% over the i7-4790K. There is a small minor issue with gaming that disappears when you use synthetics, but only to the tune of a couple of percentage points. For that minor hit, the package combo of processor, chipset and DDR4 should be an intrigue in the minds of Sandy Bridge (and older) owners.
What Happens Now?
Next on the list for us is Intel’s Developer Forum in mid-August. Here Intel has said they will present details on their Skylake architecture and it will hopefully shed some further insight into what is going on under the hood with Skylake. We will have a full write up for you after the event.
There is still the rest of the Skylake stack to be released – non overclocking processors, low power processors, and the B/H/Q chipsets too. There is no official date on these except ‘later in the year’. We will also get to these when we have more information.
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asmian - Sunday, August 9, 2015 - link
>Somehow I doubt it...Sorry, no edit - I meant of course the reverse, that 2 extra cores is DEFINITELY better than marginal extra IPC at a slightly higher overclock, despite the slightly higher TDP. Quad-core Skylake at this price AND requiring DDR4 makes Haswell-E look very good indeed.
Ethos Evoss - Sunday, August 9, 2015 - link
Why they STILL calling it i7 an i5 i3 ... they supposed to change it this time differently ..like i4 i6 i8 ?? or rather without that apples ''i'' ?
orion23 - Sunday, August 9, 2015 - link
Yay for my 2600K @ 4.8ghz from day 1Never had as much fun overclocking and building system
By now, I've changed cases (3x) and PSU's (2X), VGA's (2X). But not my loyal 2600K :)
What a workhorse it is
Kutark - Sunday, August 9, 2015 - link
I think a lot of people in the comments aren't really understanding the article. They state that the best reason to upgrade isn't really the processor speed, its all the other things the new platform affords you.In particular im very happy that i will FINALLY be able to get an SSD with speeds faster than what SATA3 allows as many of the motherboard for the z170 have m.2 thats not running on sata but on PCIE channels. It also allows for some real bandwidth in SLI situations. I have a single 980ti, and this platform would allow me to SLI another down the road and not impede things.
Granted, its not a good value proposition when you look at the end result, but its a very nice future proofing platform in my opinion.
Its kind of like saying if you have a modded older mustang thats as quick as a new mustang that you shouldn't upgrade because its just as or maybe slightly faster. There are more factors to the equation. Things that add to the quality of life, etc.
In skylake's its mostly stuff related to the chipset. IMO thas fine by me.
sonny73n - Wednesday, August 12, 2015 - link
I think you're an idiot. Understanding the article is one thing, realizing how close it is to the truth is another. Sure it's a nice upgrade for anything prior to Sandy Bridge but the author has summed up this article with a bold statement "Sandy Bridge, Your Time Is Up" which I believe - a false statement. Should I have a 5th grader break down the calculation of upgrade options so you can understand? First, note to mind that there's no such thing as future proofing in PC hardwares like you said and K series are made for overclocking.Let break down the upgrade options for my rig - Z68 MB $190, 2500K $230, HSF $60, 8GB RAM $60, PSU $180, GTX 780 $480, SSD $180, Case $80. Total $1460.
Option 1: Upgrade MB, CPU, HSF and RAM. Old components ($540 new) can eBay for ~$200. New components $560 - $200 = $360 (out of pocket). Performance gain: System Overall 30%, Gaming 3 to 5%.
Option 2: Upgrade the whole system. Total $1480. Performance gain same as option 1. Now having 2 systems (wonder what I'm gonna do with both).
Option 3: Upgrade for gaming. Another GTX 780. Performance gain: BF3 1920x1200 4xAA about 95%. Total $480.
Sure Skylake has some new features. Do I need them? NO. Do my SSD saturate SATA3 bus (throughput around 550MB/s)? NO. Is there any program (beside Handbrake which I use rarely) that can utilize the full power of my 2500K OCed mildly at 4.2GHz? NO. Can 980ti SLI saturate PCI-e2.0? NO. Am I such an idiot that I have a good running Mustang but I still like to buy another just because it's a bit better? NO. Is being financially irresponsible add to the quality of life? NO.
Anyone with a brain that has a SB system or newer would never pick the first 2 options.
mapesdhs - Wednesday, August 12, 2015 - link
If there was a thumbs-up button for your post, I'd be clicking it. :Dsonny73n - Thursday, August 13, 2015 - link
Thanks :-) I wish I could explain it better. He's probably wondering why there's a $20 different lol. Hint CPUKutark - Thursday, August 20, 2015 - link
This is pretty hilarious and just further proves my point. You had a fundamental misunderstanding of what the article is stating. You also have a fundamental understanding of the concept of an opinion. This article is not a encyclopedia brittanica article trying to create statements of fact. It is the OPINION of this website that sandy bridge's time is up. I tend to agree with them. And i'm on sandy bridge.Like most internet heroes, you're focusing on one aspect, price/performance. People buy products for a multitude of other reasons. Just simply getting a pure speed upgrade isn't always the primary factor behind the decision.
For example, i bought a VW GTI a few years back instead of a Mazdaspeed 3, even though the mazdaspeed 3 was a better performing car, and was cheaper. I bought the VW because of the intangibles. I liked the way it drove, i liked the interior design better, the exterior design better, etc etc etc.
I will be buying a skylake platform because i like the options the chipset affords me moving forward, in particular the increased number of PCI express lanes which will come in useful when m.2 pcie SSD's come down in price.
And please don't talk to me about financial responsibility. We're not talking about buying a $500k house when you can really only afford a $300k house. Most of us make enough money that while $1k isn't insignificant, it's not going to break the bank either. Get your head out of your ass.
But, please, continue on making an ass of yourself, if nothing it is entertaining...
FullCircle - Monday, August 10, 2015 - link
I'm still happy with my SandyBridge i7-2600k.I see no reason to upgrade for 25% performance boost...
I just upgraded my graphics card from GTX 580 to GTX 970, giving me a performance boost of 250%... now that's a worthwhile upgrade...
25% on the other hand? That's not worth it. CPU advancement has slowed so much there's not much reason to upgrade at the moment unless you have an incredibly old processor. Even the Core i7 processor I have in my old PC is still pretty good.
mapesdhs - Wednesday, August 12, 2015 - link
I upgraded from 3GB 580 SLI to one 980 and even that was a good speed increase. Rocking along with a 5GHz 2700K. For a 2nd system to drive a 48" TV, I considered HW, but in the end for the games I'll be playing (which can use more than 4 cores) a used SB-E build made a lot more sense. ASUS R4E only 113 UKP, 3930K only 185 UKP, etc. Only key item I bought new was another 980.It's pretty obvious with hindsight that Intel jumped ahead much more than they needed to with SB/SB-E, so we won't see another leap of that kind again unless AMD or some other corp can seriously compete once more, just as AMD managed to do with Athlon64 back in the day. All this stuff about bad paste under the heat spreaders of IB, HW and still with SL proves Intel is dragging its feet, ditto how lame the 5960X compares to XEONs wrt its low clock, TDP, etc. They could make better, but they don't need to. Likewise the meddling with the PCIe lanes for HW-E; it's crazy that a 4820K could actually be better than a 5820K in some cases. Should have been the other way round: 5820K should have been the 6-core low end with 40 lanes, next chip up at current 5930K pricing should have been an 8-core with 40 lanes, 5960X should have been an 8 or 10 core with 64 or 80 lanes (whatever), with a good 3.5 base clock, priced *above* the current 5960X a tad - that would have been a chip the real enthusiasts with money to burn would have bought, not the clock-crippled 5960X we have atm.