At its Siggraph 2014 booth, Intel is showing off one of the first public demos of DirectX 12 and Direct3D 12 — and the improvement over older graphics APIs, such as DirectX 11, is really quite startling. The exact same demo under DirectX 12 consumed 50% less power than the DirectX 11 version. In a similar demo, the higher efficiency and lower overheads of DX12 allowed for a 60% increase in frame rate over DX11 while consuming the same amount of power. After an awful lot of talk about the benefits of Mantle, DirectX 12, and OpenGL NG, it’s very exciting to see an example of the actual real-world gains of these new graphics APIs.

Intel’s DirectX 12 demo setup consists of a Surface Pro 3 tablet and a custom-made benchmarking program. The program draws 50,000 asteroids on the screen, each with a unique combination of vertices, textures, and constants. A graph in the bottom right corner of the window shows the current power consumption of both the CPU and GPU. The program can switch between DirectX 12 and 11 with the click of a button. If you were wondering why Intel is running the demo instead of Microsoft: The original Surface Pro 3, with a Core i5 chip, has Intel HD4400 graphics.

The benchmark has two modes. The first mode locks the frame rate, which keeps the hardware load constant, allowing you to see the power consumption difference between DX12 and 11. The second mode unlocks the frame rate, allowing the CPU and GPU to try as hard as possible to score the max fps. The results, as you can see from the various images throughout this story, are pretty dramatic.

In the image above, the demo starts off in DX11 mode — and then at the half-way point DX12 is enabled. CPU usage instantly drops, reducing overall power consumption (according to Microsoft) by 50%.

In the images below, with the benchmark in “unlocked” mode, you can see how switching between DirectX 11 and 12 affects the frame rate. DX11 manages 19 fps, while DX12 is more than 60% faster at 33 fps — at the same power consumption.

In both cases, the lower power consumption and higher frame rates are achieved by reducing CPU overhead — which is the main purpose of DirectX/Direct3D 12, AMD’s Mantle, OpenGL NG, and Apple’s Metal. Basically, current graphics libraries (DX11, OpenGL 4) make extensive use of the CPU. The newer graphics libraries allow developers to write graphics code that runs directly on the GPU, rather than going via the CPU. Once upon a time it made sense to go via the CPU, but now it’s just seen as unnecessary overhead.

Reducing CPU utilization obviously reduces overall power consumption — or, alternatively, in the case of integrated GPUs, a cooler CPU means the nearby GPU has more thermal headroom to deliver higher frame rates. In both cases, DirectX 12 could be a very big deal for mobile devices (laptops, smartphones, tablets), where power consumption and integrated GPUs rule the roost.

The benefit of low-overhead graphics libraries on desktop PCs and game consoles is not so clear. On a modern desktop PC, the CPU isn’t much of a bottleneck — and if you have a discrete graphics card, its thermal envelope obviously isn’t linked to the CPU. As we reported last week, at least one developer thinks DirectX 12 won’t help the Xbox One hit 1080p @ 60 fps — the Xbox One is limited by a weak GPU, and new libraries like DX12 can’t do anything about that.

In any case, an overall reduction in power consumption is always nice. If DirectX 12 can drop my PC’s total power consumption by 20 or 30 watts — about $10-20 per year — then I can buy a couple more Steam games when they’re on sale!