Intel’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.

What You Can Buy: Gaming Benchmarks on High End GPUs
POST A COMMENT

475 Comments

View All Comments

  • silverblue - Thursday, August 6, 2015 - link

    A "tweaked 8-core Ph2"? Putting aside the fact that significant changes would've been required to the fetch and retire hardware (the integer units themselves were very capable but were underutilised), a better IMC and all the modern instruction sets that K10 didn't support, AMD had already developed its replacement. It probably would've buried them to have to shelve Bulldozer (twice, it turns out) and redevelop what was essentially a 12-year old micro-architecture.

    AMD were under pressure to deliver Bulldozer hence the cutting of corners and the decision to go with GF's poor 32nm process as they simply didn't have any alternative (plus I imagine they were promised far more than GF could deliver). Phenom II was not enough against Nehalem, let alone Sandy Bridge.

    Blaming Intel doesn't help either as AMD couldn't exactly saturate the market with their products even when they were fabbing them themselves, however I think the huge drop in mainstream CPU prices when Core 2 was released along with the huge price paid for ATi did more damage than any bribing of retailers and systems manufacturers.
    Reply
  • nikaldro - Wednesday, August 5, 2015 - link

    40% over excavator, with 8 cores, good clockspeeds and good pricing doesn't sound that bad. I'll wait till Zen comes out, then decide. Reply
  • Spoelie - Thursday, August 6, 2015 - link

    IPC difference between piledriver and skylake amounts to 80%... Lets hope excavator's IPC is better than anticipated and 40% is sandbagging it a bit.

    Given AMD's track record of overpromising and underdelivering, I'm afraid Zen will massively disappoint.
    Reply
  • Asomething - Thursday, August 6, 2015 - link

    Well it will only be behind by something like 15-25% if the difference between piledriver and skylake is 80% since piledriver to excavator is supposed to be a good 20% jump. If amd can manage to catchup in any meaningful way and make chips that can touch 5ghz then things might turn out ok. Reply
  • mapesdhs - Thursday, August 6, 2015 - link

    Catchup will not be good enough. They need to be usefully competitive to pull people away from Intel into a platform switch, especially business, who have to think about this sort of thing for the long haul, and AMD's track record has been pretty woeful in this regard. I hope they can bring it to the table with Zen, but I'll believe it when I see it. Highly unlikely Intel isn't planning to either splat its prices or shove up performance, etc., if they need to when Zen comes out, especially for consumer CPUs. We know what's really possible based on how many cores, TDP, clock rates, etc. are used for the XEONs, but that potential just hasn't been put into a consumer chip yet.
    Remember, Intel could have released an 8-core for X79, but they didn't because there was no need; indeed the 3930K *is* an 8-core, just with 2 cores disabled (read the reviews). Ever since then, again and again, Intel has held back what it's perfectly capable of producing if it wanted to. The low clock of the 5960X is yet another example, it could easily be much higher.
    Reply
  • MapRef41N93W - Friday, August 7, 2015 - link

    You're assuming it's going to be a flat 40% over Excavator and not a best case scenario 40% (like every single AMD future performance projection always is...). It's more than likely a flat 20% IPC increase which puts it even behind Nehalem IPC wise.

    Top off the fact that it's AMD's first FinFET part (look at the penalty Intel paid in clockspeed with the transition to FinFET with IB/HW) and a transition to a new scalable uARCH (again look at the clockspeed hit Intel took when going from Netburst to scalable core arch, very similar to what AMD is doing now actually) and I can see Zen parts clocking horribly on top of that. Being on a Samsung node that is designed with low power in mind won't help their case either.

    You may get an 8 core Zen part for $300-$400 but it probably won't clock worth a damn and end up at 3.5-4GHz on average. So it would be a much worse choice than a 5820k for most people.
    Reply
  • mapesdhs - Wednesday, August 12, 2015 - link

    Btw, I wasn't assuming anything about Zen, I really haven't a clue how it'll compare to Intel's offerings of the day. I hope it's good, but with all that's happened before, I hope for the best but expect the worst, though I'd like to be wrong. Reply
  • Azix - Friday, August 21, 2015 - link

    You guys are being pretty negative on AMD. AMD tried to do an 8core chip on 32nm, maybe that was their mistake. The market wasn't even ready considering how long that way and where we are now. I do think intel got them pretty badly with their cheating

    The next processors are on a much better process. Based on the process alone we would expect a significant bit more performance than some seem willing to allow. Not to mention the original architecture was designed on a 32nm process. It's no surprise it would fall that far behind intel who is currently on 14nm. As time progresses though, those process jumps will take intel longer and longer. AMD will be much closer. Next year will be the first these two are on the same process (similar anyway). in a long while and it will last till at least 2017. AMD should be able to pick up some CPU sales next year and hopefully return to profitability. Intel also enjoys ddr4 support.

    Stop pushing old 32nm architectures and crappy motherboards.
    Reply
  • SkOrPn - Tuesday, December 13, 2016 - link

    Well if you were paying attention to AMD news today, maybe you partially got your answer finally. Jim Keller yet again to the rescue. Ryzen up and take note... AMD is back... Reply
  • CaedenV - Wednesday, August 5, 2015 - link

    Agreed, seems like the only way to get a real performance boost is to up the core count rather than waiting for dramatically more powerful single-core parts to hit the market. Reply

Log in

Don't have an account? Sign up now