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The Intel Core i9-9900KS Special Edition Review: 5.0 GHz on All the Cores, All the Time

Intel's Core i9-9900KS arrives with impressive gaming performance.

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Our stock setups for both AMD and Intel processors use the vendor-specified stock memory frequency. We tested the overclocked -9900K/S models at DDR4-3600 to highlight the performance advantages of memory tuning. 

Test results annotated with "PBO" reflect performance with AMD's auto-overclocking Precision Boost Overdrive feature activated. Those configurations also run at DDR4-3600. 

VRMark and 3DMark

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(Image credit: Future)

We aren't big fans of using synthetic benchmarks to measure performance, but 3DMark's DX11 and DX12 CPU tests provide useful insight into the amount of horsepower available to game engines.

As expected, the Ryzen 9 3900X takes a commanding lead during these benchmarks, largely because the tests scale well with extra threads. The overclocked Core i9-9900KS does come close to matching AMD's flagship, but falls short. 

The -9900KS redeems itself in VRMark, which favors per-core performance. The Ryzen 9 3900X falls to the bottom of the chart, while the tuned Ryzen 7 3700X beats the stock -9900K. 

Civilization VI AI and Stockfish

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(Image credit: Future)

Stockfish, an open-source chess engine, is the perennial world leader in computer chess competitions, beating other engines like Google's Deepmind AlphaZero. The engine is designed to extract the utmost performance from many-core chips, so it scales well up to 512 cores. That parallelism hands the 24-thread Ryzen 9 3900X a convincing win. 

Civilization VI's AI performance test is highly dependent on per-core performance, which plays well to the Core i9-9900KS's strengths as it takes the uncontested lead. We tuned the overclocked Core i9-9900K configuration with DDR4-3600 memory, while the stock -9900KS operates at its standard DDR4-2666. The KS still manages to pull off the win against its counterpart.  

Ashes of the Singularity: Escalation

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(Image credit: Future)

The stock Core i9-9900KS matches the overclocked -9900K step for step, while tuning both the chip's cores and memory allows it to take a decent lead over the fully-overclocked -9900K, not to mention the overclocked Ryzen 9 3900X.

At stock settings, however, the -9900KS's advantage over the stock -9900K is slight.


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Paul Alcorn
Paul Alcorn
Managing Editor: News and Emerging Tech

Paul Alcorn is the Managing Editor: News and Emerging Tech for Tom's Hardware US. He also writes news and reviews on CPUs, storage, and enterprise hardware.

68 Comments Comment from the forums
  • Aspiring techie
    If my memory serves me correctly, the Stockfish chess engine got stomped by Google's Deepmind AlphaZero, not the other way around.
    Reply
  • atavax
    Why isn't one of the Cons the security vulnerabilities in modern Intel CPUs?
    Reply
  • joeblowsmynose
    I just watched Steve Burkes review, and he notes some pretty interesting caveats with this chip ...

    The title of this article: "5.0 GHz on All the Cores, All the Time" --- is not true if it is used with a motherboard manufacturer that stuck to Intel's TDP guidelines, like Asus did.

    On Asus boards, this chip only boosts all core @5ghz for a limited time then drops back down to maintain reasonable power consumption, as per Intel's own TDP specification for this processor. So basically, Intel gave mobo makers specs to keep TDP ~127w but really it was just their way of lying about TDP but deferring that misinfo to the mobo makers. The mobo maker that actually chose not to allow a misleading TDP now gets punished ... sounds like an Intel move.

    So I assume this will mean that Asus is going to be pissed with Intel since gigabyte and MSI boards will let it suck all the power it needs to maintain 5ghz -- completely disregarding the TDP is the only way it boosts at 5ghz all cores, full time.

    So how this chip performs has far more to do with the mother board, than the chip. This is stupid.


    As an aside question ... what's the cooling power required for OCing? The OC testing here was done using 720mms worth of radiators on a custom loop - what's next ... LN2 testing? ;) We know the limit is somewhere between the H115i and the dual rad custom loop, but I wonder where that is. A lot of cooling for any OCing anyway it seems ... (but expected).
    Reply
  • colson79
    I find it sort of annoying how all these reviews always talk about how much better gaming performance is on Intel but leave out the fact that that is only 1080P or lower. The push Intel like it's the only choice for gamers without mentioning the fact that almost every game has the same performance with resolutions over 1080P. I haven't gamed on a 1080 P resolution for years. I think a lot of less informed people completely skip AMD as an option because these review sites push the Intel 1080 P benchmarks so hard. At a minimum I think they should include the 2k and 4k benchmarks in their CPU reviews.
    Reply
  • PCWarrior
    joeblowsmynose said:
    I just watched Steve Burkes review, and he notes some pretty interesting caveats with this chip ...On Asus boards, this chip only boosts all core @5ghz for a limited time then drops back down to maintain reasonable power consumption, as per Intel's own TDP specification for this processor.
    If "Out of the box" was literally meant to mean “no bios fiddling whatsoever” then stock behaviour should also be with the XMP profile disabled as you need to get into the bios in order to enable it. And for ASUS boards, the moment you go to enable XMP, it prompts you to load optimised defaults which removes power limits. Also it should be pointed out that no-power-limits and MCE are not the same thing and are not viewed as the same thing by Intel. Reviewers like Steve Burkes from Gamers Nexus and Der8auer seem to conflate the two. They are NOT the same. No-power-limits sticks to stock turbo frequency tables (for example the regular 9900K still only boosts to the stock all-core turbo of 4.7 GHZ but instead for only 25 seconds it does so indefinitely). MCE, on the other hand, means both no-power-limits AND to make the all-core turbo boost equal to the single-core turbo boost (for example for the regular 9900K with MCE enabled it means boosting to 5GHZ on all cores indefinitely). For warranty purposes MCE is considered an overclock by Intel. No-power-limits is NOT considered an overclock by Intel. It is stock and it is left to the motherboard vendor how the settings are configured out of the box.
    Reply
  • PCWarrior
    colson79 said:
    I find it sort of annoying how all these reviews always talk about how much better gaming performance is on Intel but leave out the fact that that is only 1080P or lower.
    They use 1080p because this is currently the highest resolution where with a top GPU there is definitely a cpu bottleneck and it is therefore a cpu test. It is not a cpu test when there is a gpu bottleneck. With current gpus, even with the likes of 2080Ti, you can have an i3 8100 and still do as well in 4K gaming as with a 9900K. However fast forward to the future and using something like a 3080Ti or a 4080Ti and you will be having a cpu bottleneck across all games at 1440p and probably even at 4K. With a 3080Ti or a 4080Ti you will be getting the same fps that you currently get with a 2080Ti at 1080p but at 1440p and 4K. You can verify this by going backwards to a lower resolution. If you have a 2080Ti, you get the same fps for 720p and 1080p because in a cpu bottleneck situation fps can only increase with a better cpu, not a better gpu.
    Reply
  • joeblowsmynose
    PCWarrior said:
    If "Out of the box" was literally meant to mean “no bios fiddling whatsoever” then stock behaviour should also be with the XMP profile disabled as you need to get into the bios in order to enable it. And for ASUS boards, the moment you go to enable XMP, it prompts you to load optimised defaults which removes power limits. Also it should be pointed out that no-power-limits and MCE are not the same thing and are not viewed as the same thing by Intel. Reviewers like Steve Burkes from Gamers Nexus and Der8auer seem to conflate the two. They are NOT the same. No-power-limits sticks to stock turbo frequency tables (for example the regular 9900K still only boosts to the stock all-core turbo of 4.7 GHZ but instead for only 25 seconds it does so indefinitely). MCE, on the other hand, means both no-power-limits AND to make the all-core turbo boost equal to the single-core turbo boost (for example for the regular 9900K with MCE enabled it means boosting to 5GHZ on all cores indefinitely). For warranty purposes MCE is considered an overclock by Intel. No-power-limits is NOT considered an overclock by Intel. It is stock and it is left to the motherboard vendor how the settings are configured out of the box.

    A complicated way to lie about TDP ... lol. Whatever you say, it disingenuous.
    Reply
  • TJ Hooker
    joeblowsmynose said:
    On Asus boards, this chip only boosts all core @5ghz for a limited time then drops back down to maintain reasonable power consumption, as per Intel's own TDP specification for this processor. So basically, Intel gave mobo makers specs to keep TDP ~127w but really it was just their way of lying about TDP but deferring that misinfo to the mobo makers. The mobo maker that actually chose not to allow a misleading TDP now gets punished ... sounds like an Intel move.
    FYI this applies to all Intel CPUs with turbo boost, not just the 9900KS. Officially they're all supposed to have a limited duration boost buy nearly all mobos remove this limit. And they've been doing so for some time, so it seems Intel doesn't really care.

    Which makes sense, as it improves their benchmark scores and if anyone complains about power draw they can just point to their states rules for power levels and blame the mobo manufacturers, even though they've implicitly given them permission to do this by allowing it to go on in a widespread fashion.
    Reply
  • TJ Hooker
    Last page:
    Bear in mind that we tested with an Nvidia GeForce GTX 1080 at 1920x1080 to alleviate graphics-imposed bottlenecks.
    Should say 2080 Ti.
    Reply
  • Soaptrail
    PCWarrior said:
    They use 1080p because this is currently the highest resolution where with a top GPU there is definitely a cpu bottleneck and it is therefore a cpu test. It is not a cpu test when there is a gpu bottleneck. With current gpus, even with the likes of 2080Ti, you can have an i3 8100 and still do as well in 4K gaming as with a 9900K. However fast forward to the future and using something like a 3080Ti or a 4080Ti and you will be having a cpu bottleneck across all games at 1440p and probably even at 4K. With a 3080Ti or a 4080Ti you will be getting the same fps that you currently get with a 2080Ti at 1080p but at 1440p and 4K. You can verify this by going backwards to a lower resolution. If you have a 2080Ti, you get the same fps for 720p and 1080p because in a cpu bottleneck situation fps can only increase with a better cpu, not a better gpu.

    Yes but they should include a couple 1440p and 4K resolution benchmarks to put context. It could still be beneficial to buyers to get the cheaper options like the AMD Ryzen 3600 and upgrade in a couple years than buy the 9900KS and stick with it for 6 years.
    Reply