xda: Intel Core i7-7700k Review – A Swan Song of 8 Threads in Kaby Lake

Healthy competition is a great thing in the marketplace. In the processor segment it’s something that Intel hasn’t had to strongly challenge for years — it’s why we have seen 7 generations of the Core branding’s mainstay featuring 4 core CPUs with Hyper-threading. After the release of AMD’s processors based on the Zen architecture, our own review of the consumer Ryzen brand found that the competition is once again heating up. Intel’s already made sweeping decisions to its lineup, announcing heavier core and thread counts at Computex and rebranding the high-end desktop segment as Core X. More recently they also announced a Coffee Lake lineup that will see the departure of the mainstay 4C/8T Core i7, at least according to rumors leading up to what is widely expected to be an October 5th release. This also comes with a departure from their 3 year cycle, as Coffee Lake CPUs will require a new motherboard.

One thing was missing from our Ryzen review: benchmarks from Intel’s current mainstay Core i7, the Kaby Lake 7700k. It’s fairly similar to its older Skylake brother except in one very big detail — clock speeds. After making introductions with Intel they were kind enough to provide a sample. So now with everything in hand to do this right, it’s time to finally put this to the test. How does Kaby Lake fare against Ryzen and what does this mean in light of the upcoming 8th generation release?

Unboxing

Like most unclocked processors nowadays the 7700K came by itself. Being the first review sample I have received from Intel it took a bit to get used to seeing something other than the CPU model on the top. When inserted into the motherboard it is recognized as a standard 7700K. The base clock speed on this is indeed 4.2 GHz as listed on the lid, but Intel’s Ark website shows that it boosts to 4.5 GHz – an impressive speed given that the previous high was 4.4 GHz with the Devil’s Canyon i7-4790K.

GIGABYTE once again came through in offering a motherboard to conduct this review on. This gave us the opportunity to see if the issues with installing Linux on their motherboards, including Intel based ones, had been addressed. The motherboard they provided, the GA-Z170X-Gaming 7, indeed worked without issue and provided a surprise that the ASUS Z170I PRO GAMING didn’t – the board also featured a USB Type-C port that was Thunderbolt 3.0 compatible. We’ll be coming back to this motherboard soon to put that to use.

Testing Hardware Setup

Now with a separate motherboard and having switched the personal PC from the i7-6700K to a Ryzen 7 1700X we’re exclusively down to the test bench for testing, as it should be. So we’ll break down the common elements and then distinguish what was different between AMD and Intel configurations. All items were not purchased directly by XDA, and I state who provided each non-purchased component in the list below.

Software/Operating System

Ubuntu 17.10
Phoronix Test Suite – current using apt

Photos

Overclocking

For the sake of the testing at their fullest potential, both the 1600X and 1800X were also tested at their max supported overclock of 3.9 GHz. Intel’s processors allowed for much more overclocking, easily using presets in the Z170-GAMING 7 to hit 4.5 GHz for the Skylake 6700k as well as a whopping 5 GHz for the Kaby Lake 7700k. This will apply to the benchmarks that we provide below.

Non-Build Benchmarks

Benchmark Notes: Phoronix Test Suite’s CPU suite offers a plethora of tests and not all will be included in this review. The full test results from the Phoronix Test Suite are available on Openbenchmarking.org site. I am adding a link here for the comparison of all results.

FFTW

FFTW is a single-threaded benchmark of fast Fourier transform. Differences between Ryzen 6 and 8 core models are fairly similar and overclocking doesn’t do much here. On the other hand, Intel’s scores easily show why it is the king of single threaded performance. Noteworthy here is that while overclocking doesn’t bump up Ryzen much, Intel sees notable gains by overclocking.

GZip Compression

GZip is a common compression method and so it makes sense to check out the performance here. GZip is also another single-threaded test so not a big surprise to see Intel coming out on top. What is also interesting is that in this case we see nearly a 25% decrease in time over the Ryzen 7 1800X at its fullest potential. The LZMA test also provided similar results.

SciMark 2 (Java) v1.3.0

The SciMark 2 benchmark utilizes Java for arithmetic operations and then provides scoring based on those results. This new version, unlike the previous Ryzen test, gave us much lower numbers across the board. Also where the composite seems to have been better for Ryzen, this new version definitely shows a clear winner in Intel.

John The Ripper

On the cryptography front, John The Ripper offers similar results as the Ryzen review. The multi-threaded nature of this benchmark allows it to tap well into the additional cores and threads for maximum performance. Both the 6700k and 7700k allow it to keep up fairly well against the Ryzen 1600X despite having 2 less cores and 4 less threads, so it will be interesting to see how Coffee Lake fares in these tests with additional cores.

C-Ray v1.1

C-Ray also continued the multi-threaded results that we saw in the Ryzen review. AMD’s additional cores in Ryzen allow it to outperform in these multi-threaded tests. What is finally better to see is a clear break between 4, 6 and 8 cores with SMT enabled, something that was not as clear in the Ryzen review. As cores increase we see a rough decrease of 30% at 2 additional, and about 45% with 4 additional. Here we can understand some of the reasons why Intel may be saying goodbye to the stalwart 4C/8T Core i7.

Benchmarks: Build Performance

Build Test: ImageMagick

This one is very interesting because what we would have expected did not always happen. The 1600X outperformed the 1800X at stock speeds, yet did slower than its own stock build when overclocked. Intel’s 6700k and newer sibling, the 7700k, easily hold within and see greater reductions in build time from overclocking, enough that they are within striking distance of AMD’s Ryzen 7 counterpart.

Build Test: PHP

Much like the ImageMagick test Intel’s 7700k beats out the 1600X. It even comes within striking distance of beating the 1800X, despite having half the core and thread count. Well played, Intel.

Build Test: LineageOS cm-14.1 Pixel XL

Since Google is about to embark on a second generation of the Pixel lineup I thought it’s a good time to review which device we’re testing LineageOS builds with. As a result we’ve gone away from the Nexus 6P and instead are using the Pixel XL for these and upcoming benchmarks. As requested by readers the graph will display both build times without cache (in grey) and using CCACHE (in blue.)

Across the board we see an increase in build times, which isn’t surprising given that we changed models. Once again we see what we can now likely extrapolate out to as a trend. Intel’s build times are impressive, and when it comes to cached build times it even beats out the 1800X by a little bit. It seems the additional speed that can be extracted from the 7700K here is paying off. But when we get to non-cached builds, we’re finally seeing good returns on higher thread and core counts.

Intel Core i7-7700K Final Thoughts

When it comes to single threaded performance and IPC, Intel shows that even despite offering fewer cores and threads than AMD’s Ryzen, it knows where its stronghold is and is playing to its strengths. But unlike many other reviews that were done at the launch of Kaby Lake, this review gives a reflection of how times have changed since then. It’s clear that Ryzen has changed the landscape and offers a competitive choice to consumers. Intel’s response has been somewhat murky in the high-end desktop range. On the mainstream consumer side, though, the rumors suggest that we’ll see the i7 increased from 4 to 6 cores, which will offer an additional 4 threads.

Based on the benchmarks we see above, those rumored additional cores should be enough to even top the Ryzen 7 1800X in many cases. But I personally don’t understand why we’re hearing that Intel’s stalwart of 4 cores and 8 threads is being removed from the lineup. I am hoping that it’s just to introduce the higher core counts first and then offer these somewhere in the new Coffee Lake lineup, perhaps either as a lower end i7 or i5. The fact that both the i3 and i5 lineups lacking HTT doesn’t sit well with me, despite the additional cores. Regardless, if the rumors are true, readers may not have to wait much longer to find out. Several embargoes have been announced for October 5th, suggesting that this will be the day that Coffee Lake is unveiled to the public. I hope we’ll see something there saying that the current understanding is incorrect and we’ll see them again. But if that’s not the case, Intel’s truly brought the best out of the 4C/8T Core i7 to date with the 7700K. They should be proud of what they’ve accomplished in this final masterpiece, a technical swan song of its consumer mainstay CPU as it has been for these seven generations.

But what if you were building right now? If so you’ve got a great choice on your hands. If IPC, single-threaded performance or overclocking headroom pique your interest, Intel’s got you covered. If you need Thunderbolt 3 support prior to next year, you’re still with Intel and this would be the logical choice at this time. Intel makes no bones about its strengths and, despite many who expected a different result, has not adjusted pricing differently based on the release of Ryzen. Ryzen does offer better multi-threaded performance and lower build times without cache, and it does so at competitive pricing to this product. The smartest move right now if you’re building? Wait a month and see what Coffee Lake brings to the table. Since almost all students are in school already, there probably isn’t a pressing matter for many to build right away — and that month’s wait should offer great clarity on where the industry is going for the late fall through spring of 2018. Even if you’re considering upgrading from an older i7, the required motherboard change makes it worth waiting to see whether or not Coffee Lake is worth jumping on.

Never before did Intel change the basic core and thread count in nearly 8 years of the brand. Even when they offered a budget CPU like the G4560 they moved it to the Pentium branding. So while Coffee Lake will keep the Core branding alive for at least the next 18 to 24 months, this really is the end of a significant chapter in Intel’s history. And, to someone that has followed this brand closely, I feel like I’m saying goodbye to a good friend with the 7700K. If this is indeed the farewell of the 4C/8T mainstream flagship by Intel, you will be sorely missed. And to that, may we raise a toast to the Core i7-7700K — truly at the top of Intel’s game with this core and thread count.

Readers: We’d like to know – what did you think of this review? For those of you who are considering upgrading, did this help you make an informed decision? Maybe you already own one and want to share your experiences with it? Sound off on this and other parts of reviews in the comments below, Facebook, Twitter or Google+! And if you enjoyed this review, please kindly share it with others! We look forward to your feedback!

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mercredi 13 septembre 2017

Intel Core i7-7700k Review – A Swan Song of 8 Threads in Kaby Lake