Windows 10 is finally here! Before reading any further, do yourself a favour and grab your free copy.

Done? Fantastic. Windows 10 is not just a UI spruce-up. It’s not even mobile-desktop convergence that we’re going to talk about. Windows 10, and DirectX 12 in particular, are huge for gamers. Usually, the old adage that “there’s no such thing as a free lunch” holds true, whether you’re talking about graphics cards, exam results, or…free lunches, but DirectX 12 – exclusive to Windows 10 – will effectively give you a 20 per cent boost in performance, as compared to DX11. Of course, games will have to support the DirectX 12 rendering path, but that’s a given for titles releasing later this year. Here’s a technical lowdown of why the new DirectX 12 API is a big thing for PC gamers.



What’s DirectX?

DirectX is the name given to Microsoft’s graphics API – short for Application Program Interface. Basically, an API is what sits between a piece of hardware and the software you want to run on it. Graphics APIs like DirectX are what sit between your GPU and your game software. Why is this important? Well, let’s consider it this way: Remember the PlayStation 1? In terms of specs, the PSOne has an incredible…2 Megabytes of RAM and a 33 MHz processor. There are graphing calculators these days that are more powerful than that.

Yet, the PS1 was able to run full 3D games with basic lighting and shadows. A modern high-end Android smartphone is, all said and done, roughly ten times more powerful than a PS2, which is in turn ten times more powerful than the PSOne. So why is it that, in its day, the PS1 ran graphically intensive titles reasonably well while even flagship devices today have trouble coping with graphically intensive games?

Star Wars Knights of the Old Republic is a good example. This is a title released on the original Xbox. Yet my phone, the Asus Zenfone 2, with a quad-core Intel Atom processor clocked at 2.3 GHz, a PowerVR G6430 GPU that outdoes the PS3 in certain benchmarks, and 4 GB of RAM (that’s 64 times as much as the original Xbox had), lags hard in the game unless all the settings are turned down as low as they can go.

This is because of a little thing called API overhead. The original Xbox didn’t have much of an operating system. There wasn’t much sitting between the “metal” of the hardware and the software, so the machine could be used to its absolute full potential. On the other hand, the Zenfone 2 runs on Android, and uses the OpenGL graphics API, which has a tremendous amount of overhead. In English, that means OpenGL is incredibly wasteful and doesn’t do a very good job of interfacing between the hardware and the software, so most of the potential of that PS3-beating GPU is wasted.


When it comes to Windows, the situation is not quite as dire. Microsoft’s own DirectX has come a fairly long way in the past 20 years. DirectX 11, the API that’s been favoured since around 2011, brought performance improvements over DX9 and DX10 (and 10.1). Moreover, at the high end, cards like the Nvidia GTX 980 Ti are simply so powerful that they brute force their way through API overhead, bottlenecks, and whatever else that may come in their way. But there’s a lot of room for improvement.

With Windows 10, Microsoft is debuting DirectX 12. The most interesting aspect of DX12 is that it focuses on eliminating API overhead by providing better low-level access. While developers may never be able to “code right to the metal” like they could with the PSOne and the original Xbox, DX12 gives them substantially better access to the underlying hardware. Moreover, MS is touting DX12’s ‘multiadapter’ functionality as a major performance booster. Under DX12, instead of relying on just one graphics card – or two of the same kind in SLI/Crossfire – multiadapter allows all graphics components installed in the system, whether they’re AMD parts, Nvidia parts, or the onboard Intel graphics adapter, to work on the graphics rendering task.

While mixing AMD and Nvidia hardware is not likely to be of major use, tapping in to the power of integrated Intel HD Graphics adapters is likely to yield at least an additional 5-10 per cent of performance. Multiadapter, together with DX12’s focus on low-level access, means that as an average gamer, you can expect a 20 per cent or greater improvement in framerates compared to DX11. This is quite literally free performance we’re talking about here. With DX12 exclusive to Windows 10, this alone makes it a worthwhile upgrade.