GPU Scaling

Switching gears, let’s take a look at performance from a GPU standpoint, including how well Star Swarm performance scales with more powerful GPUs now that we have eliminated the CPU bottleneck. Until now Star Swarm has never been GPU bottlenecked on high-end NVIDIA cards, so this is our first time seeing just how much faster Star Swarm can get until it runs into the limits of the GPU itself.

Star Swarm GPU Scaling - Extreme Quality (4 Cores)

As it stands, with the CPU bottleneck swapped out for a GPU bottleneck, Star Swarm starts to favor NVIDIA GPUs right now. Even accounting for performance differences, NVIDIA ends up coming out well ahead here, with the GTX 980 beating the R9 290X by over 50%, and the GTX 680 some 25% ahead of the R9 285, both values well ahead of their average lead in real-world games. With virtually every aspect of this test still being under development – OS, drivers, and Star Swarm – we would advise not reading into this too much right now, but it will be interesting to see if this trend holds with the final release of DirectX 12.

Meanwhile it’s interesting to note that largely due to their poor DirectX 11 performance in this benchmark, AMD sees the greatest gains from DirectX 12 on a relative basis and comes close to seeing the greatest gains on an absolute basis as well. The GTX 980’s performance improves by 150% and 40.1fps when switching APIs; the R9 290X improves by 416% and 34.6fps. As for AMD’s Mantle, we’ll get back to that in a bit.

Star Swarm GPU Scaling - Extreme Quality (2 Cores)

Having already established that even 2 CPU cores is enough to keep Star Swarm fed on anything less than a GTX 980, the results are much the same here for our 2 core configuration. Other than the GTX 980 being CPU limited, the gains from enabling DirectX 12 are consistent with what we saw for the 4 core configuration. Which is to say that even a relatively weak CPU can benefit from DirectX 12, at least when paired with a strong GPU.

However the GTX 750 Ti result in particular also highlights the fact that until a powerful GPU comes into play, the benefits today from DirectX 12 aren’t nearly as great. Though the GTX 750 Ti does improve in performance by 26%, this is far cry from the 150% of the GTX 980, or even the gains for the GTX 680. While AMD is terminally CPU limited here, NVIDIA can get just enough out of DirectX 11 that a 2 core configuration can almost feed the GTX 750 Ti. Consequently in the NVIDIA case, a weak CPU paired with a weak GPU does not currently see the same benefits that we get elsewhere. However as DirectX 12 is meant to be forward looking – to be out before it’s too late – as GPU performance gains continue to outstrip CPU performance gains, the benefits even for low-end configurations will continue to increase.

CPU Scaling DirectX 12 vs. Mantle, Power Consumption
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  • Alexey291 - Friday, February 6, 2015 - link

    It can be as free as it likes. In fact for all I care they can pay me to install it... Still not going to bother. And you know why? There's no benefit for me who only uses a Windows desktop as a gaming machine.

    Not a single one. Dx12 is not interesting either because my current build is actually limited by vsync. Nothing else but 60fps vsync (fake fps are for kids). And it's only a mid range build.

    So why should I bother if all I do in Windows at home is launch steam (or a game from an icon on the desktop) aaaand that's it?
  • Nuno Simões - Friday, February 6, 2015 - link

    Clearly, you need to read the article again.
  • Alexey291 - Saturday, February 7, 2015 - link

    There's a difference in a benchmark. Well surprise surprise. On the other hand games are likely to be optimised before release. Even games by Ubisoft MIGHT be optimised somewhat.

    So the difference between dx11 and 12 will be imperceptible as usual. Just like the difference between ten and eleven was even though benchmarks have always shown that 11 is more efficient and generally faster.
  • Nuno Simões - Saturday, February 7, 2015 - link

    So, it's faster and more efficient, but that's worthless?

    What happened between 10 and 11 is that developers used those improevments to add to substance, not speed, and that is probably going to happen again. But anyway you see it, there is a gain in something. And, besides, just the gains from frametimes and lower buffers is worth it. Less stutter is always a good thing.

    And the bad optimisation from some developers is hardly DX's fault, or any other API for that matter. Having a better API doesn't suddenly turn all other API's into s*it.
  • inighthawki - Saturday, February 7, 2015 - link

    What are you blabbering on about? No benefit? Fake fps? Do you even know anything about PCs or gaming?
  • Alexey291 - Saturday, February 7, 2015 - link

    You don't actually understand that screen tearing is a bad thing do you? :)
  • Murloc - Saturday, February 7, 2015 - link

    I've never seen screen tearing in my life and I don't use vsync despite having a 60 Hz monitor.

    Fact is, you and I have not much to gain from DX12, apart for the new features (e.g. I have a dx10 card and I can't play games with the dx11 settings which do add substance to games, so it does have a benefit, you can't say there is no difference).

    So whether you upgrade or not will not influence the choices of game engine developers.
    The CPU bottlenecked people are using 144Hz monitors and willing to spend money to get the best so they do gain something. Not everybody is you.

    Besides, I will be upgrading to windows 10 because the new features without the horrible w8 stuff are really an improvement, e.g. the decent copy/paste dialog that is already in w8.
    Add the fact that it's free for w8/8.1 owners and it will see immediate adoption.
    Some people stayed on XP for years instead of going to Vista before 7, but they eventually upgraded anyway because the difference in usability is quite significant. Not being adopted as fast as you some guy on the internet think would be fast enough is no excuse to stop development, otherwise someone else will catch up.
  • inighthawki - Saturday, February 7, 2015 - link

    I well understand what screen tearing is, but not locking to vsync doesn't suddenly make it 'fake FPS.' You literally just made up a term that means nothing/. You're also ignoring the common downside of vsync: input lag. For many people it is extremely noticeable and makes games unplayable unless they invest in low latency displays with fast refresh rates.
  • Margalus - Saturday, February 7, 2015 - link

    it does make it "fake fps" in a way. It doesn't matter if fraps is telling you that you are getting 150fps, your monitor is only capable of showing 60fps. So that 150fps is a fallacy, you are only seeing 60fps. And without vsync enabled, those 60fps that your monitor is showing are comprised of pieces more than one frame in each, hence the tearing.

    but other than that, I can disagree with most everything that poster said..
  • inighthawki - Saturday, February 7, 2015 - link

    Correct, I realize that. But it's still not really fake. Just because you cannot see every frame it renders does not mean that it doesn't render them, or that there isn't an advantage to doing so. By enabling vsync, you are imposing a presentation limit on the application. It must wait until the vsync to present the frame, which means the application must block until it does. The faster the GPU is at rendering frames, the larger impact this has on input latency. By default, DirectX allows you to queue three frames ahead. this means if your GPU can render all three frames within one refresh period of your monitor, you will have a 3 frame latency (plus display latency) between when it's rendered and when you see it on screen, since each frame needs to be displayed in the order it is rendered. With vsync off, you get tearing because there is no wait on presents. The moment you finish is the moment you can swap the backbuffer and begin the next frame. You always have (nearly) the minimal amount of latency possible. This is avoidable with proper implementations of triple buffering that allow the developer to discard old frames. In all cases, the fps still means something. Rendering at 120fps and only seeing 60 of them doesn't make it useless to do so.

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