Skip to main content

Intel Core i5-8600K Review: Coffee Lake's Jolting Value

Our Verdict

The Core i5-8600K leverages its extra two cores to great effect in threaded workloads, offering a substantial boost over its predecessor while aggressive Turbo Boost bins ensure great performance in lightly-threaded workloads. An easy overclocking experience, paired with excellent gaming performance that rivals previous-generation Core i7 models, will make the Core i5 series a heavily sought after processor for enthusiasts.

For

  • Strong performance in both games and productivity applications
  • Competitive with previous-gen Core i7 models
  • Overclocking headroom

Against

  • Z-Series Motherboard requirement
  • Requires Heatsink

Meet Intel's First Six-Core Core i5

For years, Intel dominated the high-end CPU market. As a result, enthusiasts had to pay a premium for its best processors. But AMD's four-, six-, and eight-core Ryzen models forced Intel to reconsider its value story. Our recent Core i7-8700K review showed that the company is serious about defending its turf. The six-core Coffee Lake-based flagship maintained the architecture's strength in lightly-threaded tasks, while extra Hyper-Threaded cores improved its performance in the heavy workloads AMD is doing so well in.

A $390 price tag is painfully expensive for most power users, though. That's why Tom's Hardware historically recommended Intel's unlocked Core i5 models to gamers. So how does the new Core i5-8600K fare against Core i7-8700K and, perhaps more important, AMD's Ryzen 7 and 5 CPUs?

Intel Core i5-8600K

Like the Core i7-8700K, Core i5-8600K sports six physical cores based on Intel's Skylake architecture. Hyper-Threading is disabled, similar to previous-generation Core i5 models. However, we still expect significant speed-ups across our benchmark suite thanks to higher clock rates and core count. Core i5-8600K features a similar graphics engine as its predecessor (never mind the UHD Graphics 630 branding), though it does benefit from a 50 MHz boost to 1150 MHz.

At the heart of Coffee Lake is Intel's 14nm++ manufacturing process. Delaying 10nm transistors forced the company to further refine its 14nm node. Attractive power optimizations, such as 52%-lower leakage than the original 14nm process, play a key role in enabling higher core counts within the same TDP envelope. Improved manufacturing yields higher performance as well; despite Core i5-8600K's more complex die, its 4.3 GHz peak Turbo Boost frequency is still higher than Core i5-7600K's 4.2 GHz ceiling.

14nm Broadwell (2014)14nm Skylake (2015)14nm+ Kaby Lake (2017)14nm++ Coffee Lake (2017)
Maximum Turbo Frequency (GHz - Core i7 family)3.84.34.54.7
Estimated Maximum Overclock Frequency (GHz - Conventional Cooling)4.14.65.05.2

Of course, incrementally-higher peak clock rates are great. But adding 50% more cores promises to have a much more significant impact on the threaded benchmarks in our suite. Those workloads are the ones that AMD currently dominates. Intel did have to sacrifice base frequency in order to wedge six cores into a 95W TDP, though. Whereas the -7600K guaranteed 3.8 GHz across four cores, Core i5-8600K's base rate is 3.6 GHz. Consider this, though. With Turbo Boost enabled and four cores active, the -7600K hits 4 GHz. Core i5-8600K can take four cores up to 4.2 GHz, while its six-core bin maxes out at 4.1 GHz.

Active Cores1246
Intel Core i5-8600K 4.3 GHz4.2 GHz4.2 GHz4.1 GHz
Intel Core i5-7600K 4.2 GHz4.1 GHz4.0 GHz-

We also get a few extra cache slices as a byproduct of the additional cores, so the -8600K features 9MB of L3, compared to -7600K's 6MB. Memory improvements play a role in Coffee Lake's higher performance, too. The -8600K supports up to DDR4-2666, moving up to 42.7 GB/s across two 64-bit channels, versus DDR4-2400's 38.4 GB/s.

As we discussed in Core i7-8700K Review: Coffee Lake Brews A Great Gaming CPU, Intel improved the trace layout on Z370 motherboards to support the increased memory transfer rate. It also revised the power alignment inside the LGA 1151 interface to better accommodate the new six-core CPUs. This means you can't drop Coffee Lake-based processors into Z270 or Z170 motherboards. The requirement is a technical one, though that obviously doesn't make enthusiasts who recently purchased Z270 platforms feel any better.

Core i5-8600K's unlocked multiplier fits well with the Z-series boards, which are needed in order to manipulate its ratio. Intel also added a few new overclocking knobs and dials, such as per-core overclocking support, live memory timing adjustments, and memory multipliers up to 8400 MT/s. Like all of Intel's K-series processors, you're on the hook for a thermal solution; Core i5-8600K doesn't come with an air- or closed-loop liquid cooler.

Beyond the price of a heat sink or all-in-one, you're also looking at a steep premium over Core i5-7600K. Street pricing on the -8600K is currently $280, while the -7600K sells for $240. AMD's Ryzen 5 1600X is also available at $240, and the recently price-reduced Ryzen 7 1700 sits right around $300. Going the Ryzen route gives you the option of a lower-cost B350-based motherboard. And as if AMD's story needed strengthening, a bundled Wraith Spire cooler all but guarantees you could have an 8C/16T platform for less money than Intel's 6C/6T alternative. As always, we'll have to rely on the benchmarks to guide our recommendations.


MORE: Best CPUs


MORE: Intel & AMD Processor Hierarchy


MORE: All CPUs Content

  • logainofhades
    Great CPU, but the overall platform cost is a bit of a turn off, for me. I'd rather get a 1600, and a B350 board, to allow for a better GPU, if buying new. As stated in the review, even a 1700, with a less expensive board, is a very compelling option.

    Reply
  • AS118
    Seems like a good product, but I'd like to see what the 8600 and 8500 non-k offers, and perhaps next year with the B360 boards that give them a more budget "locked cpu" option.

    I also feel that the availability will be low for Coffee Lake until the end of this year, particularly throughout the holiday season. Due to that concern (as well as the total cost of platform ownership) I think that Ryzen with its 1600 and 1700 CPU's along with the 1600x will be the value kings this year, with Coffee Lake not hitting it's stride until early next year.

    The fact that AMD's stuff doesn't have the same availability issues makes it a strong contender, imho, although Black Friday and Christmas sales will also like make Kaby Lake (and even Sky Lake) stuff at clearance prices appealing too, despite the lack of cores you'll find in Ryzen and now Coffee Lake.
    Reply
  • almostdecent
    Since the chart shows the i5-8600k and the i5-8600K@4.9GHz at the same $260, I presume that means you achieved the overclock with the stock cooler.
    Reply
  • ammaross
    It's kind of disappointing to see so many benchmarks where an i5 does as well or better than it's i7 counterpart. It just shows how poorly threaded some of these applications really are and almost necessitates running two benchmarks simultaneously to really judge the merit of these multi-core CPUs. Maybe run the photoshop test while rendering with After Effects or run a game benchmark while doing CPU h.265 handbrake.
    Reply
  • almostdecent
    It is worth mentioning that this is essentially a paper launch at the moment, since none of the Coffee Lake processors are available anywhere.

    http://www.nowinstock.net/computers/processors/intel/
    and the rare place that has any, such as Microcenter, have gouging prices. Such as selling the plain i7-8700 (not the K version) with an MSRP of $300 for sale for $429.

    http://www.microcenter.com/product/486087/Core_i7-8700_Coffee_Lake_32_GHz_LGA_1151_Boxed_Processor
    Reply
  • InvalidError
    20281291 said:
    I also feel that the availability will be low for Coffee Lake until the end of this year, particularly throughout the holiday season.
    On September 20, Intel responded to a story about yet another 10nm schedule slip by saying that Cannon Lake will begin shipping in limited quantities to some laptop manufacturers with production ramping up in 1H2018. Limited Coffee Lake volume could be due to Intel deciding to upgrade production lines to 10nm for Cannon Lake instead of 14++.
    Reply
  • TJ Hooker
    20281420 said:
    Since the chart shows the i5-8600k and the i5-8600K@4.9GHz at the same $260, I presume that means you achieved the overclock with the stock cooler.
    Not sure if you were being sarcastic, but the 8600K doesn't have a stock cooler.

    There are two different sets of graphs, one that looks at CPU only costs and the other that considers CPU, mobo, and cooler costs. In the latter, the 8600K at 4.9GHz is clearly shown to cost more.
    Reply
  • InvalidError
    20281420 said:
    Since the chart shows the i5-8600k and the i5-8600K@4.9GHz at the same $260, I presume that means you achieved the overclock with the stock cooler.
    Intel hasn't included a stock HSF with their unlocked CPUs since Skylake so on top of paying more for the unlock, you also get shafted by the price of a stock cooler which you no longer get on top of it. You need an aftermarket cooler for both stock and OC.

    Same thing with AMD's Ryzen nnnnX CPUs.
    Reply
  • YoAndy
    20281216 said:
    Great CPU, but the overall platform cost is a bit of a turn off, for me. I'd rather get a 1600, and a B350 board, to allow for a better GPU, if buying new. As stated in the review, even a 1700, with a less expensive board, is a very compelling option.

    A better GPU?//Why would you do that. at 1080p Ryzen will (bottleneck) hold back powerful GPU's, It won't give you equal performance. I bought a Ryzen for pure gaming and i ended up selling it..
    Reply
  • acosta.87
    20281216 said:
    Great CPU, but the overall platform cost is a bit of a turn off, for me. I'd rather get a 1600, and a B350 board, to allow for a better GPU, if buying new. As stated in the review, even a 1700, with a less expensive board, is a very compelling option.

    B350 VRM's are pretty low quality for any sort of OC unless it's a mild one so for me that's a no go. If you're primarily into gaming then the 1600 has nothing on the i5, it simply trails it whether at stock settings or OC'd and even at productivity it beats a 1600 Ryzen processors in most task even with a 6 thread deficit so it's a pretty good investment overall.
    Reply