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If all goes to plan, Microsoft's next-gen API will usher in a new standard for visuals and performance across a whole range of devices, from high-end PCs, to modest laptops, to even the Xbox One. But the extent in which each platform will benefit from the new software is a matter for debate. Xbox One developers, in particular, have tempered their expectations, with none going as far as publicly claiming that the difference will be day and night. Other developers and publishers, meanwhile, have suggested that the API will pave the way for meaningful enhancements to visual fidelity and performance on PC. But how far can DirectX 12 go? Below, GameSpot provides a guide explaining how each platform is expected to benefit from DirectX 12 support, explaining each of its key new features step by step.  DirectX 12 on Xbox OneSmarter Graphics RenderingOn the Xbox One, DirectX 12 could bring about meaningful improvements to its games and the system as a whole. The Xbox One currently works through DirectX 11, with several tweaks made specifically for the system. In many ways, using the older API of DirectX 11 had limited the full potential of Xbox One, with developers being forced to using an older, less efficient API. In particular, using DirectX 11 prevented the system from using Asynchronous shaders (or Async shaders), which spreads the graphical load across multiple threads, and lets the system compute it simultaneously, rather than having to wait for the graphics queue to finish up before moving to the next job. In theory, DirectX 12 could speed up the time it takes to usually render post-processing effects. Async Shaders are something that the PlayStation 4 already uses in a variety of games such as Infamous: Second Son (the Async shaders helped the PS4 render the particle effects seen in-game). A similar effect will likely come to Xbox One games utilising similar rendering methods. In practice, this means more rendering ability, potentially paving the way for enhanced visual effects. Unlocking the potential of eSRAM The biggest update coming with the DirectX 12 update is a complete revamp in how the Xbox One's 32Mb of superfast eSRAM is used. Many developers believed that the way the Xbox One's eSRAM API was a pain to use. However with the DirectX 12 update, Microsoft has introduced a new tool to specifically optimise eSRAM usage. In the company's own SDK Documentation for DirectX 12 (which leaked in January), it has specifically stated that "optimising to reduce memory bandwidth usage (Of the eSRAM) is a key strategy for Xbox One." This could potentially boost performance of the system, and result in a slight bump in performance in future games and titles. That suggests, but doesn't quite guarantee, that more Xbox One games will render at the same resolution and framerate as PlayStation 4 games. A Faster Dashboard and 4K PossibilitiesThe boost that DirectX 12 gives the Xbox One is not strictly limited to performance bumps in-game. Phil Spencer, the head of the Xbox division, has expressed an interest in speeding up the responsiveness of the console's dashboard. During a recent discussion with a fan on Twitter, who asked Spencer whether the Xbox One's system software would take advantage of the upcoming DirectX 12 API, he replied: "Yes, dashboard can take full advantage of [DX12] platform features." "The Xbox One Dashboard can take full advantage of DX12 platform features."
He added that a more fluid Xbox One UI is "high on the list of improvements we want to make." In another discussion with a fan, Spencer expressed a desire and potentially displaying content in 4K. More on how feasible this is later. Curb Your EnthusiasmSo far, developers have been somewhat conflicting with regards to how the performance of the Xbox One will be improved with DirectX 12. Damien Monnier, senior game designer at CD Projekt RED, recently suggested that DirectX 12 would not likely solve the issues the Xbox One has with resolution with certain games, stating that "resolution changes would require a much bigger change from Microsoft than DX12 upgrade." Brad Wardell, CEO of Stardock and developer behind upcoming title Ashes of the Singularity, sits on the opposite side of the fence, remaining positive about the API upgrade and claiming that it could potentially solve the Xbox One’s resolution woes. “I do think it'll largely address the Xbox One resolution issue but that is speculation,” he recently stated.
The full impact of DirectX 12 on Xbox One will not be perfectly clear until developers begin to utilise it in practice. Along with conflicting statements from developers, we are not completely certain as to how much the update will impact the system on a technical level. We can however tell that it would give the system a welcome push in efficiency that will help the Xbox One in the long run.  DirectX 12 on PCUnlocking More GPU Power With MultiadapterArguably the biggest feature of DirectX 12 on PC is the GPU Multiadapter. Since Microsoft has developed the new API to be low level, it allows a "deeper" access to the hardware that can unlock the unused power of graphics processing units inside your system. This processing is brand-agnostic and can combine the power of an integrated GPU as well as external cards. On the DirectX Developer Blog, Microsoft explains that performance can be enhanced by around 10 percent just by utilising a CPU's integrated graphics. According to Microsoft's tests, this does add a frame of latency, however the boost that the extra power gives should even things out. This means that if you just have an integrated GPU onboard your CPU, you should see tangible benefits once developers start to utilise this feature. This boost in performance is achieved by dividing the workload across all of the hardware available instead of attempting to process it all on one single card. The way that this extra power is being used is completely up to software developers on a case-by-case basis. It's possible that the system will use a "Master" GPU, which will carry the brunt of the heavy lifting, leaving the other GPUs to handle tasks such as post-processing. In addition to this, the Multiadapter is also able to pool VRAM between external GPUs. Which essentially means that the larger RAM pool can handle bigger textures, meaning more efficient rendering at higher resolutions, such as 4K. Windows 10 is expected to launch along with DX12 in late 2015Backwards Compatibility with DirectX 11 CardsMicrosoft is pushing the release of DirectX 12 alongside Windows 10 to maximise the adoption of its new operating system, and coming along with it is a host of game-changing features. But the best news? The DirectX 12 API will be compatible with all DirectX 11 class GPUs shipped, which eliminates the absolute necessity to upgrade your card or system to enjoy the benefits of DirectX 12. Of course, for the best jump in performance, you'll need to upgrade your GPU, especially if your card is more than two years old. GameTech's DirectX 12 API Overhead TestWe tested DirectX 12 in 3DMark's API Overhead test, which measures how fast your CPU and GPU communicate with one another by sending "Draw Calls" and then rendering it onscreen. The slower the API, the less we will see onscreen. The benchmark tests three different APIs; DirectX 11's single threaded performance, DirectX 11's multithreaded performance, and DirectX 12's multithreaded performance. Basically, the more draw calls per second, the faster the performance being pushed out of the same hardware. One thing to note about this, is that it is not a CPU or GPU test, and doesn't measure the performance of the components themselves, but instead measures the driver behind it. For our test we used an Intel i5 2500k and a GeForce GTX 970 across all three APIs.  The results are pretty staggering, with DirectX 11's single threaded performance at 1.4 Million Draw calls per second, the multithreaded performance at 2.1 Million and DirectX 12's multithreaded performance at 13.1 Million per second. This all sounds amazing, however, bear in mind that this is just a simple test showcasing the efficiency of the new API. It does not exactly reflect the real-world performance that DirectX 12 would have in-game. This test shows us how the new API harnesses the power within multi-core CPUs in a more efficient manner, letting it communicate with the GPU even faster. Once developers start using the DirectX 12 API, we could see the requirement for a multi-core CPU become a standard in games, due to just how incredibly efficient the DirectX 12 API is in using multiple CPU threads. Fact or Fantasy? Square Enix's DirectX 12 ShowcaseMicrosoft has bundled all of these new features into a quite staggering showcase of DirectX 12 with a demo by Square Enix, titled "WITCH - Chapter 0 [cry]". The demo was seen running on a bank-busting four Nvidia GTX Titan X cards in SLI. With the sheer processing power and DirectX 12 in tow, the demo touted over 63 Million polygons per scene and was also rendered with 8k by 8k textures. This level of graphical fidelity is a scintillating tease of the future, a look into the potential of DirectX 12 and the ever-improving power of external GPUs. It may take some time for game developers to utilise the power of the Multiadapter and DirectX 12, but the potential gains from the new API are too great to ignore. This demo is essentially a showcase of rendering power and technology that we're likely to see from mainstream games in the coming years, and boy does it look pretty. DirectX 12 on low-end systems The benefits of DirectX 12 on PC are not strictly limited to high-end gaming systems, but also standard mobile devices and notebooks. Intel has showcased benchmarks running on a Surface Pro 3, using a Core i5 CPU with an Intel 4400 internal GPU. The Benchmark is split into two modes, one running a fixed framerate benchmark at 19 frames-per-second, which can flick between DirectX 11 and DirectX 12. In this particular benchmark, we see that when switched to DirectX 12, the CPU power consumption plummets dramatically by what Microsoft claims is 50 percent. As for the second benchmark, the framerate is unlocked, and when switched from DirectX 11 to 12, the framerate jumps from 19FPS to 33FPS. This shows, in theory, that even lower end systems should be able to enjoy a jump in performance and power once the new API is widely adopted by developers. From these tests that we can see that DirectX 12 on PC has a dramatic effect upon systems of all kinds, from the high-end all the way to the lower-end of GPUs. DirectX 12's 4k FutureIt's clear that DirectX 12 will have a significant long-term effect on both PC and Xbox One with a clear, forward-looking focus on rendering games, content and video at 4K. Ian Bell, head of the development team behind Project CARS, was asked recently what he believed would be the benefits of utilising Direct X 12. His laconic response: "30-40 percent". Because the new API's true capabilities remain to be seen on the Xbox One, it's not completely clear whether or not the update will serve to extend the console's performance. On the PC side, it's looking like DirectX 12 will have a profound effect on almost every PC capable of running Windows 10, but the real gains will be found when developers start using the GPU Multiadapter in new, innovative ways to optimise performance. Microsoft still needs to ensure that DirectX 12 marks a technological leap that will see tangible benefits to gamers everywhere, but for now, an exciting future lies ahead. DirectX 12 is due to roll out Holiday 2015 on both Xbox One and PC.
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