Part 1: DirectX 11 Gaming And Multi-Core CPU Scaling

We test five theoretical Intel CPUs in 10 different DirectX 11-based games to determine what impact core count has on performance.

Our Broadwell-E: Intel Core i7-6950X, 6900K, 6850K & 6800K Review presented us with an interesting opportunity to compare four-, six-, eight-, and 10-core processors in productivity and gaming software. Most of the results aligned with what we expected to see—applications optimized for multiple cores scaled well all the way up to Intel’s flagship Core i7-6950X, while notoriously single-threaded metrics only responded to clock rate and the IPC improvements baked into more modern architectures.

But some of the numbers piqued our curiosity. For instance, Ashes of the Singularity ran faster as we added more cores at 2560x1440—a traditionally graphics-bound resolution. F1 2015 also appeared to exploit whatever host processing resources we threw at it. And naturally, 3DMark’s Physics sub-test loved the extra physical and logical cores. Bioshock Infinite was the only game that favored our Core i7-6700K’s Skylake architecture and 4 GHz+ clock rate.

This got us wondering a few things. How many of today’s popular games do, in fact, demonstrate optimizations for more than four cores? What happens when we go the other way and throw a dual-threaded processor into the mix? As we discussed the idea internally, the premise for a grander experiment emerged. We’d take five Intel CPUs, ranging from two to 10 cores, turn off Hyper-Threading on all of them and set each to operate at the same clock rate. We chose three current Broadwell-E models (Core i7-6950X, -6900K, and -6850K) and two Skylake-based CPUs (Core i7-6700K and Core i3-6320).

Mixing the different architectures might seem like a liability, but the two desktop-class Broadwell processors that we could have used add their own variables to this equation. Besides, the introduction of Skylake will make it easier to identify the games unable to utilize more than four cores; in those benchmarks, Core i7-6700K should finish in first place. Otherwise, we should have a well-controlled environment for comparing various core configurations. The only other influences would come from different-sized L3 caches and memory subsystems (two channels versus four).

In this first part of the story, we’re selecting 10 different DirectX 11-based games to compare. Later, we’ll take a sampling of DirectX 12- and Vulkan-based titles and see how CPU utilization changes under next-gen APIs.

As an added bonus, we sat down with three development teams to talk about the work that went into optimizing their engines for multi-core CPUs in today’s titles, and what they’ll be able to do in the future. A lot of this information is brand new, and you won't want to miss it.

How We Tested

As mentioned, we chose five CPUs to compare: Intel’s Core i7-6950X, -6900K, -6850K, -6700K, and Core i3-6320. Between them, we have everything from two to 10 cores at our disposal, with locked and unlocked multipliers facilitating an even 3.9 GHz across the board. Remember, this isn’t a buying guide. Our purpose is to figure out how the games we like to benchmark will respond to core count.

Answering that question also requires a fast enough GPU to keep graphics from becoming an immediate bottleneck. A single GeForce GTX 1080 Founders Edition card is about as quick as they come. However, the work your GPU does changes dramatically with resolution. That is to say we could dial in a super-low resolution and generate viable results. But we wanted to go a step further and test using some of the settings that show up in our reviews. To that end, we have charts reflecting performance at 1920x1080, 2560x1440, and 3840x2160.

The other platform components play less of a role in determining the outcome of our experiment, but they're still necessary in a stable, well-balanced machine. We're using MSI’s Z170A Gaming M7 motherboard, MSI’s X99A Gaming Pro motherboard, 32 GB of G.Skill DDR4-3200 Trident Z memory in four 8 GB modules, Crucial’s 500 GB MX200 SSD, and be quiet!’s Dark Power Pro 850 W.

  • DirectX 11, Extreme quality preset, built-in benchmark

  • DirectX 11, Ultra quality preset, custom Tom’s Hardware benchmark (Tashgar jeep ride), 100-second Fraps recording

  • DirectX 11, Ultra quality settings, built-in benchmark (test five), 110-second Fraps recording

  • DirectX 11, Ultra level of detail, FXAA, High texture quality, built-in benchmark, 95-second Fraps recording

  • DirectX 11, Very High detail settings, built-in benchmark, 145-second Fraps recording

  • DirectX 11, Ultra detail preset, built-in benchmark, 40-second Fraps recording

  • DirectX 11, Ultra quality settings, High anti-aliasing, High texture resolution, Nürburgring Sprint, 100-second Fraps recording

  • DirectX 11, Very High detail settings, built-in benchmark, 80-second Fraps recording

  • DirectX 11, Very High detail settings, Supersampling temporal AA, built-in benchmark, 90-second Fraps recording

  • DirectX 11, Highest quality settings, HairWorks disabled, custom Tom’s Hardware benchmark, 100-second Fraps recording

MORE: Best Graphics Cards

MORE: Desktop GPU Performance Hierarchy Table

MORE: All Graphics Content

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    Top Comments
  • Nolonar
    Wouldn't it have been a more representative benchmark if you just used the same CPU and limited how many cores the games can use?
    14
  • Other Comments
  • ledhead11
    Awesome article! Looking forward to the rest.

    Any chance you can do a run through with 1080SLI or even Titan SLi. There was another article recently on Titan SLI that mentioned 100% CPU bottleneck on the 6700k with 50% load on the Titans @ 4k/60hz.
    3
  • Nolonar
    Wouldn't it have been a more representative benchmark if you just used the same CPU and limited how many cores the games can use?
    14
  • Traciatim
    Looks like even years later the prevailing wisdom of "Buy an overclockable i5 with the best video card you can afford" still holds true for pretty much any gaming scenario. I wonder how long it will be until that changes.
    3
  • nopking
    Your GTA V is currently listing at $3,982.00, which is slightly more than I paid for it when it first came out (about 66x)
    7
  • TechyInAZ
    Anonymous said:
    Looks like even years later the prevailing wisdom of "Buy an overclockable i5 with the best video card you can afford" still holds true for pretty much any gaming scenario. I wonder how long it will be until that changes.


    Once DX12 goes mainstream, we'll probably see a balanced of "OCed Core i5 with most expensive GPU" For fps shooters. But for CPU the more CPU demanding games it will probably be "Core i7 with most expensive GPU you can afford" (or Zen CPU).
    1
  • avatar_raq
    Great article, Chris. Looking forward for part 2 and I second ledhead11's wish to see a part 3 and 4 examining SLI configurations.
    0
  • problematiq
    I would like to see an article comparing 1st 2nd and 3rd gen I series to the current generation as far as "Should you upgrade?". still cruising on my 3770k though.
    1
  • Brian_R170
    Isn't it possible use the i7-6950X for all of 2-, 4-, 6-, 8-, and 10-core tests by just disabling cores in the OS? That eliminates the other differences between the various CPUs and show only the benefit of more cores.
    3
  • TechyInAZ
    Anonymous said:
    Isn't it possible use the i7-6950X for all of 2-, 4-, 6-, 8-, and 10-core tests by just disabling cores in the OS? That eliminates the other differences between the various CPUs and show only the benefit of more cores.


    Possibly. But it would be a bit unrealistic because of all the extra cache the CPU would have on hand. No quad core has the amount of L2 and L3 cache that the 6950X has.
    1
  • filippi
    I would like to see both i3 w/ HT off and i3 w/ HT on. That article would be the perfect spot to show that.
    1
  • littleleo
    I think the price for GTA V is setting the gold standard in game pricing $3982, and it is a little... okay a it's a lot lot lot more then I would ever pay for a game. I've bought cars for less money, ouch!
    2
  • littleleo
    I've sold more i5 gaming systems since the 1st iCore CPUs came out up to today. It would have been nice to have at least 1 i5 I don't think we needed 4 i7s. Since the ratio to i3s and especially i5s they are a much much smaller segment.
    0
  • artk2219
    It would be nice to see a run with AMD's FX's in the mix since they give you threads, but its at the cost of IPC, and since you can get an FX 8320e for $89.99 (or an FX 6300, but why would you bother at that price) at Microcenter, for those of us lucky enough to be near one. You can spec out the main components of your build (mobo, cpu, mem, and cooler) for $200 to $220. Or a full build without a great graphics card for $350 to $400. With a good graphics card it can be a great value, atleast once you bump the clocks on the 8320e (4.0 ghz or so).
    3
  • footman
    Great article, very important to add the results of the dual core cpu when hyperthreading was enabled. For all of the current games requiring quad core, i believe that a dual core that has hyperthreading will work just as well then.....
    1
  • littleleo
    Anonymous said:
    It would be nice to see a run with AMD's FX's in the mix since they give you threads, but its at the cost of IPC, and since you can get an FX 8320e for $89.99 (or an FX 6300, but why would you bother at that price) at Microcenter, for those of us lucky enough to be near one. You can spec out the main components of your build (mobo, cpu, mem, and cooler) for $200 to $220. Or a full build without a great graphics card for $350 to $400. With a good graphics card it can be a great value, atleast once you bump the clocks on the 8320e (4.0 ghz or so).
    Microcenter is evil I tell you, EVIL!!! Plus they are a 2 hour drive in traffic from my house, yuk! Their CPU in store specials are awesome. I bought my CPU there back in the day cheaper then I could get it at cost wholesale.
    1
  • TerryLaze
    Seeing GPU being bottlenecked at lower resolutions and going on to test up to 4k ... genius!
    Also agree that the i3 should have been tested with both HT on and off.
    0
  • whtfish
    Great article, but I too would like to see where the i3 with HT on would slot in.
    2
  • AlistairAB
    Bizarre to not take the opportunity to show the i3 with HT on and off in each graph.
    1
  • none12345
    I wouldnt touch a 2 core at this point for a gaming computer. Sure you can get away with it, but no thanks.

    4 core is enough today, but it wont be tomorrow. Its not even enough today if you do something else besides 1 thing at a time on a computer. Ie if you are playing a game and doing something else on a 2nd monitor, or video capture while playing the game, or anyhting else. You need more cores if you multitask.

    Im in the market for a new cpu, but i will not consider a quad core at this point either. Quad core has been milked by intel for WAY too long; its 6+ core or nothing for me at this point. And seeing as how intel loves to ream you for its enthusiast platform, i guess its nothing for now.

    Help me zen kanobe, your my only hope! (assuming it doesnt suck, and assuming its priced reasonably)
    2
  • iam2thecrowe
    Anonymous said:
    Wouldn't it have been a more representative benchmark if you just used the same CPU and limited how many cores the games can use?


    Good point. I think it would have been an even better idea, to under-clock the cpu's to say 2-2.5ghz, and use the lowest possible resolution. This way you completely remove any bottlenecks, and the focus would be purely on the number of cores to determine core scaling. In most of these cases, an 8 core could possibly be just bottle-necked vs a 4 core, and that is the reason you don't see the performance increase.
    1