At Computex this past week, five was the magic number. Usually, it was describing the number of gigahertz certain Intel processors were clocked at during the company’s keynote. One of those demos has touched off a firestorm about just how valid it is to demonstrate a 28-core CPU with an extreme overclock and extreme cooling, but the other 5-GHz chip Intel showed is a product you can actually buy today. In exchange for $425 at Amazon, Newegg, and Best Buy, the Core i7-8086K is meant to celebrate 40 years of the x86 instruction set architecture. It’s also making a little history of its own as Intel’s first processor to reach 5 GHz Turbo Boost speeds.
Intel didn’t send review samples of this chip, but I wanted to see just what that 5 GHz number meant in practice for a stock-clocked CPU. I ordered one off Amazon with my own hard-earned cash to put it to the test. Ever since that shipment arrived Saturday, we’ve been exploring the behavior and performance of the i7-8086K.
|Core i7-8086K||5 GHz||4.6 GHz||4.5 GHz||4.4 GHz||4.4 GHz||4.3 GHz|
|Core i7-8700K||4.7 GHz||4.6 GHz||4.5 GHz||4.4 GHz||4.4 GHz||4.3 GHz|
So how did Intel get to that 5 GHz figure? Simple: Turbo Boost 2.0 relies in part on an “n-cores-active” heuristic. Put simply, fewer active cores mean the highest clocks from Turbo Boost’s multi-variate frequency-scaling management. Each chip has a number of Turbo bins equal to the number of cores on the die.
With one core active, the Coffee Lake Core i7-8700K that the i7-8086K is derived from can boost all the way up to 4.7 GHz. The Core i7-8086K’s top Turbo bin is 5 GHz. Once you get outside those numbers, the i7-8700K and i7-8086K are identical. Scuttlebutt had suggested the i7-8086K might have a more aggressive Turbo table across the board, but that’s not the case. That fact makes sense, of course, given that the chip’s TDP remained the same as its less-special sibling’s.
We’ll exhaustively tease out what this change in Turbo tables means for stock-clocked performance in a moment, but outside of web browsing, common desktop tasks, and the like, that 5-GHz figure probably won’t make itself felt. It’s nice, for sure, but I’ll stop you right here: it’s no reason to go spend $75 more on one of these over a Core i7-8700K if you want a Coffee Lake part. To really get the most out of this chip, you need to take full advantage of its unlocked multiplier.
Our initial overclocking efforts with the Core i7-8700K yielded a 5-GHz all-core Turbo speed with an AVX offset of -2 for SIMD-heavy workloads like Blender and Handbrake. That led to some jaw-dropping performance in CPU-bound games and single-threaded benchmarks, even if AMD’s Ryzen 7 1700 could often catch up in productivity workloads when pushed to 4 GHz. The mitigations for the Spectre and Meltdown vulnerabilities have dropped some ice in the coffee since, but the overclocking headroom of Coffee Lake cannot be denied. It’s the one thing AMD’s Ryzen CPUs can’t even hope to match.
I dived into some tentative overclocking efforts during our live unboxing and benchmarking of the i7-8086K this past weekend, and I’ve been refining our stable overclock since. It must be noted that every chip will overclock differently thanks to the vagaries of silicon lithography, but our sample was able to reach 5.1 GHz on all of its cores at a slightly-higher-than-conventionally-accepted-as-safe 1.38 V. Better yet, the chip can sustain those clocks with both AVX and non-AVX workloads. We have two Core i7-8700Ks in the TR labs, and neither one can stably exceed 5 GHz with the aforementioned -2 AVX offset.
I may still delid and re-paste our chip to explore its very limits, as regular workloads with those clocks and voltages are causing it to crest 90° C package temperatures under a Corsair H110i 280-mm liquid CPU cooler. I suspect I might be able to eke 5.2 GHz non-AVX clocks out of my chip with lower temperatures, as well. Perhaps we’ll do that live, too. For now, let’s see how the i7-8086K performs.
Our testing methods
As always, we did our best to deliver clean benchmarking numbers. We ran each benchmark at least three times and took the median of those results. Our test systems were configured as follows:
|Processor||Intel Core i7-8086K||Intel Core i7-8700K|
|CPU cooler||Corsair H110i 280-mm closed-loop liquid cooler|
|Motherboard||Gigabyte Z370 Aorus Gaming 7|
|Memory size||16 GB (2x 8 GB)|
|Memory type||G.Skill Trident Z DDR4-3866 (rated) SDRAM|
|Memory speed||3400 MT/s (CPUs at stock), 3866 MT/s (CPU OC)|
|Memory timings||16-16-16-36 2T|
|System drive||Samsung 960 Pro 512 GB NVMe SSD|
|Processor||AMD Ryzen 7 2700X|
|CPU cooler||EK Predator 240-mm closed-loop liquid cooler|
|Motherboard||Gigabyte X470 Aorus Gaming 7 Wifi|
|Memory size||16 GB (2x 8 GB)|
|Memory type||G.Skill Sniper X DDR4-3400 (rated) SDRAM|
|Memory speed||3400 MT/s (actual)|
|Memory timings||16-16-16-36 1T|
|System drive||Samsung 960 EVO 500 GB NVMe SSD|
Where applicable, our overclock for the Core i7-8086K was 5.1 GHz all-core with 1.38 V and no AVX offset. Our Core i7-8700K OC was 5 GHz with a -2 AVX offset and 1.35 V. While our Ryzen 7 2700X was not overclocked, its Precision Boost 2 all-core clock speed was observed to be 4.075 GHz under AVX workloads. Leaving the chip’s 4.3-GHz stock single-core Turbo speed intact is more helpfull to the 2700X than pushing for a marginally higher all-core speed like 4.2 GHz.
Some other notes on our testing methods:
- All test systems were updated with the latest firmware, graphics drivers, and Windows updates before we began collecting data, including patches for the Spectre and Meltdown vulnerabilities where applicable. As a result, test data from this review should not be compared with results collected in past TR reviews. Similarly, all applications used in the course of data collection were the most current versions available as of press time and cannot be used to cross-compare with older data.
- Our test systems were all configured using the Windows Balanced power plan, including AMD systems that previously would have used the Ryzen Balanced plan. AMD’s suggested configuration for its CPUs no longer includes the Ryzen Balanced power plan as of Windows’ Fall Creators Update, also known as “RS3” or Redstone 3.
- Unless otherwise noted, all productivity tests were conducted with a display resolution of 2560×1440 at 60 Hz. Gaming tests were conducted at 1920×1080 and 144 Hz.
Our testing methods are generally publicly available and reproducible. If you have any questions regarding our testing methods, feel free to leave a comment on this article or join us in the forums to discuss them.
Memory subsystem performance
Let’s kick off our tests with some of the handy memory benchmarks included in the AIDA64 utility.
No surprises here. Our overclocked chips are using DDR4-3866 versus the DDR4-3400 memory in our stock-clocked configs, and that translates to higher bandwidth and lower latencies.
Some quick synthetic math tests
AIDA64 offers a useful set of built-in directed benchmarks for assessing the performance of the various subsystems of a CPU. The PhotoWorxx benchmark uses AVX2 on compatible CPUs, while the FPU Julia and Mandel tests use AVX2 with FMA.
The Ryzen 7 2700X may put up a win in the SHA-accelerated win in the CPU Hash benchmark, but the superior floating-point throughput of the Coffee Lake parts is otherwise on full display. Oddly, the i7-8086K falls behind the i7-8700K in the double-precision Mandel benchmark despite its win in the single-precision Julia test. Let’s see how these synthetic performance tests bear out in actual workloads.
Our browser benchmarks are primarily single-threaded, so they should allow the i7-8086K’s 5-GHz top Turbo bin to rear its head from time to time.
The WebXPRT 3 benchmark is meant to simulate some realistic workloads one might encounter in web browsing. It’s here primarily as a counterweight to the more synthetic microbenchmarking tools above.
The i7-8086K barely beats out the i7-8700K in WebXPRT 3, although it does open a bit more of a lead over the overclocked, OG Coffee Lake i7 when we turn the screws.
Our single-threaded tests suggest one will see little difference in real-world usage from an i7-8086K versus an i7-8700K in their system. Let’s see if the chip can distinguish itself better in more multithreaded testing.
Compiling code with GCC
Our resident code monkey, Bruno Ferreira, helped us put together this code-compiling test. Qtbench records the time needed to compile the Qt SDK using the GCC compiler. The number of jobs dispatched by the Qtbench script is configurable, and we set the number of threads to match the hardware thread count for each CPU.
The practically identical Turbo tables of the i7-8700K and i7-8086K play out exactly as you’d expect in this multi-threaded benchmark. Overclocking the i7-8086K does open a small lead over the i7-8700K at 5 GHz, but it’s nothing to write home about.
File compression with 7-Zip
The free and open-source 7-Zip archiving utility has a built-in benchmark that occupies every core and thread of the host system.
The i7-8086K’s results are a bit scattershot in 7-Zip. Stock-clocked results from both Coffee Lake parts are about the same, but the i7-8086K takes the compression crown versus the i7-8700K and gives it right back in decompression.
Disk encryption with Veracrypt
The accelerated AES portion of the Veracrypt benchmark seems to favor the i7-8086K’s overclocked guise, but the non-accelerated Twofish portion of the test delivers the same results on either Coffee Lake chip.
The evergreen Cinebench benchmark is powered by Maxon’s Cinema 4D rendering engine. It’s multithreaded and comes with a 64-bit executable. The test runs with a single thread and then with as many threads as possible.
Cinebench’s one-thread mode appears to let the i7-8086K stretch its single-core boost legs a bit. Single-core operation isn’t really why we run Cinebench, though.
In the multithreaded mode of Cinebench, the Coffee Lake parts are defeated handily by the Ryzen 7 2700X. There appears to be no substitute for cores in this benchmark.
Blender is a widely-used, open-source 3D modeling and rendering application. The app can take advantage of AVX2 instructions on compatible CPUs. We chose the “bmw27” test file from Blender’s selection of benchmark scenes to put our CPUs through their paces.
Blender doesn’t put more than the barest light between our Coffee Lake parts at stock speeds. Overclock both chips, though, and the 5.1-GHz all-core AVX speed of the i7-8086K seems to give it a noticeable edge over the i7-8700K. Still, the Ryzen 7 2700X takes advantage of its beefy cooler to deliver enough stock speed to eke out a narrow win over either Coffee Lake part.
Corona, as its developers put it, is a “high-performance (un)biased photorealistic renderer, available for Autodesk 3ds Max and as a standalone CLI application, and in development for Maxon Cinema 4D.”
The company has made a standalone benchmark with its rendering engine inside, so it was a no-brainer to give it a spin on these CPUs.
Sorry to repeat myself, but it’s unavoidable. The Coffee Lake parts are practically the same in performance, and they get beat out by the Ryzen 7 2700X no matter what.
Here’s a new benchmark for our test suite. Indigo Bench is a standalone application based on the Indigo rendering engine, which creates photo-realistic images using what its developers call “unbiased rendering technologies.”
The pattern continues. It’s a split decision between AMD and Intel, though. The Ryzen 7 2700X wins out in the Bedroom test scene, while the OCed Coffee Lake parts take the prize with the Supercar scene.
Handbrake is a popular video-transcoding app that just hit version 1.1. To see how it performs on these chips, we converted a roughly two-minute 4K source file from an iPhone 6S into a 1920×1080, 30 FPS MKV using the HEVC algorithm implemented in the x265 open-source encoder. We otherwise left the preset at its default settings.
Handbrake is another instance where the overclocked i7-8086K seems to be able to press a small advantage over the i7-8700K thanks to its higher AVX clocks. Stock performance is, as usual, identical.
CFD with STARS Euler3D
Euler3D tackles the difficult problem of simulating fluid dynamics. It tends to be very memory-bandwidth intensive. You can read more about it right here. We configured Euler3D to use every thread available from each of our CPUs.
Euler3D doesn’t give much of an advantage to either Coffee Lake chip, whether stock or overclocked. Perhaps gaming performance will give us something to get excited about.
Grand Theft Auto V
Grand Theft Auto V‘s lavish simulation of Los Santos and surrounding locales can really put the hurt on a CPU, and we’re putting that characteristic to good use here.
Grand Theft Auto V tends to love what Intel’s CPUs have to offer, and it shows even at stock speeds. That said, anyone hoping for a big splash from the i7-8086K at either stock or overclocked speeds can exhale now. There’s little difference in gaming performance from an i7-8700K at 5 GHz vs an i7-8086K at 5.1 GHz.
These “time spent beyond X” graphs are meant to show “badness,” those instances where animation may be less than fluid—or at least less than perfect. The formulas behind these graphs add up the amount of time our graphics card spends beyond certain frame-time thresholds, each with an important implication for gaming smoothness. Recall that our graphics-card tests all consist of one-minute test runs and that 1000 ms equals one second to fully appreciate this data.
The 50-ms threshold is the most notable one, since it corresponds to a 20-FPS average. We figure if you’re not rendering any faster than 20 FPS, even for a moment, then the user is likely to perceive a slowdown. 33 ms correlates to 30 FPS, or a 30-Hz refresh rate. Go lower than that with vsync on, and you’re into the bad voodoo of quantization slowdowns. 16.7 ms correlates to 60 FPS, that golden mark that we’d like to achieve (or surpass) for each and every frame.
To best demonstrate the performance of these systems with a powerful graphics card like the GTX 1080 Ti, it’s useful to look at our three strictest graphs. 8.3 ms corresponds to 120 FPS, the lower end of what we’d consider a high-refresh-rate monitor. We’ve recently begun including an even more demanding 6.94-ms mark that corresponds to the 144-Hz maximum rate typical of today’s high-refresh-rate gaming displays. Finally, we’ve added a 5-ms graph to see how well any of our chips sustain a scorching 200 FPS.
Given how fast our GTX 1080 Ti runs Grand Theft Auto V, it makes the most sense to start our exploration at the 8.3-ms mark. Aside from a couple giant hangs that I have no good explanation for from the overclocked i7-8086K, things shake out about as we would expect. Our unlocked Coffee Lake parts spend just vanishing amounts of time on tough frames that take longer than 8.3 ms to complete. Flip over to the 6.94-ms mark, and the Coffee Lake chips spend about a ninth of the time the Ryzen 7 2700X does past that line in the sand. Of course, we already knew how that would play out—none of these chips are really unknown quantities. Let’s see if any other games tease out major differences between our cups of Coffee.
Far Cry 5
In our observations, Far Cry 5 tends to max out a single thread, so it’s no shock that our average-FPS numbers and 99th-percentile frame times favor Intel CPUs. Even so, pushing our chips to the 5 GHz mark and beyond seems to have exposed a new bottleneck, since we’re not really getting any major changes in performance for the trouble.
The impressive performance of the Intel chips is plenty evident at the 6.94-ms mark, where both Coffee Lake chips spend less than a fourth of the time that the Ryzen 7 2700X does holding up the graphics card from outputting 144 FPS. That translates into incredibly, enviably smooth gameplay from the Intel corner of the ring, but one doesn’t have to shell out the extra for the i7-8086K to get it.
Even as it passes six years of age, Crysis 3 remains one of the most punishing games one can run. With an appetite for CPU performance and graphics power alike, this title remains a great way to put the performance of any gaming system in perspective.
Crysis 3 is still an unusual beast in that it will happily take advantage of every core and thread one can throw at it in high-refresh-rate gaming. Clock speeds matter too, though, and that means the overclocked Coffee Lake parts turn in some truly face-melting performances while feeding the GTX 1080 Ti.
Our time-spent-beyond-X graphs indicate just how gooey our visages can get. Both overclocked Coffee Lake parts spend about a second of our one-minute test run holding back our graphics card from 144 FPS. The Ryzen 7 2700X isn’t doing badly, either, but it can’t match the lofty peaks from either Coffee Lake part. Still, the Core i7-8086K and the Core i7-8700K are indistinguishable from one another.
Deus Ex: Mankind Divided
Thanks to its richly detailed environments and copious graphics settings, Deus Ex: Mankind Divided can punish graphics cards at high resolutions and make CPUs sweat at high refresh rates.
Ctrl+C, Ctrl+V. Deus Ex: Mankind Divided sure likes it some Coffee, but the i7-8086K doesn’t distinguish itself from its more pedestrian sibling at either stock clocks or 5.1 GHz.
Assassin’s Creed Origins
Assassin’s Creed Origins isn’t just striking to look at. It’ll happily scale with CPU cores, and that makes it an ideal case for our test bench.
Assassin’s Creed Origins at least gives us something to talk about. Note the spikiness in the Ryzen 7 2700X’s frame-time plot. Origins runs noticeably rougher on the Ryzen 7 2700X than it does on either Coffee Lake part. As for our Core i7 contenders, I’d be hard-pressed to pick out one from the other, whether stock or overclocked. The decrease in 99th-percentile frame times from our OC efforts is nice, but hardly noticeable.
The Ryzen 7 2700X’s weird spikiness emerges in our time-spent-beyond-50-ms graph, although the i7-8086K isn’t immune to a less-severe hitch that also ends up on the board here. Once we’re out of those troubled waters, though, the Coffee Lake parts assert their dominance in high-refresh-rate gaming once again. At our 11-ms threshold (or 90 FPS, if you prefer), the Ryzen 7 2700X holds up our graphics card for twice as long as the overclocked Coffee Lake parts do.
All told, the i7-8086K games like an i7-8700K. The extra 100 MHz we eked out has no noticeable effect on gaming performance, nor should we expect it to given that it’s only a 2% increase over what we could get from our Core i7-8700K. The i7-8086K didn’t justify its markup in either productivity or gaming, and that’s likely to make it a tough sell for anybody actually interested in using it in our final reckoning.
There are two ways to evaluate the Core i7-8086K. The first is as a commemorative curio. Intel fans who want to celebrate 40 years of x86 should probably leave theirs sealed in the box for future generations to pick over when silicon becomes a curiosity. Intel is only making so many of these, and sealed copies will likely become more and more unusual with time.
As an actual processor, the i7-8086K isn’t worth the $75 upcharge over the i7-8700K at stock speeds. Outside of its rarely-seen 5-GHz top Turbo bin, the i7-8086K performs the same as an i7-8700K the vast majority of the time. That’s because the rest of its Turbo Boost 2.0 table is identical to the i7-8700K’s. There’s only so much a chip can do within the same thermal budget. It would have been nice to see Intel really take the leash off this thing and push TDPs or implement something like its Thermal Velocity Boost feature on this chip to truly make it something special for those who don’t want to overclock.
The story changes a little—and I do mean a little—when we take advantage of the i7-8086K’s unlocked multipliers. It’s tricky to recommend a processor on the basis of its overclocking prowess alone, because no two chips will overclock alike. That said, our retail i7-8086K made it to 5.1 GHz on all cores without any AVX offset and nothing more than the usual thermal challenges of modern Intel CPUs. No i7-8700K in our labs can run at speeds higher than 5 GHz for non-AVX workloads, and they require -2 AVX offsets to remain stable.
For all that, the i7-8086K’s slightly higher overclock didn’t translate into many practical performance benefits in our tests versus a run-of-the-mill 8700K at 5 GHz. Still want to pay that $75 extra?
That behavior does suggest Intel is putting its best Coffee Lake silicon of late under i7-8086K heat spreaders, so overclockers who are looking to get the very best performance out of their chips might not mind the upcharge. Third-party retailers like Silicon Lottery offer binned, delidded i7-8700Ks for more than an i7-8086K goes for at e-tail. If the i7-8086K proves its mettle as more enthusiasts get them in their hands, the price of this CPU could be plenty reasonable for those after the very best Coffee Lake dies.
Ultimately, the i7-8086K is more of interest for its history-marking and history-making than it is as a practical processor for the enthusiast. If you want one and don’t mind the fact that you’re paying for what is essentially the pleasure of special packaging, well, fair enough. Everybody else should just buy an i7-8700K or a Ryzen 7 2700X, depending on whether high-refresh-rate gaming or multithreaded grunt is what’s called for.