To learn about the first news on DirectX 12, we must go back to last March. We were all quite excited about the initial demos, but DirectX 12 entered a kind of mild hibernation that lasted for several months. Today, the possibility has begun to circulate that DirectX 12 will provide multi-GPU support combining AMD and Nvidia graphics cards in the same computer, something that would definitely change the rules of the game.
Any enthusiast can take two or more AMD cards to combine their performance, and the same happens with Nvidia hardware. But those who try to combine the cards from both companies usually have a pretty bad time. A relatively common idea was to use the AMD card for primary processing, and the Nvidia card to handle physics, but in later versions Nvidia decided to disable PhysX when AMD hardware is detected. In other words, AMD and Nvidia aren't even willing to share a computer when it comes to graphics. The LucidLogix Hydra tried to offer a common ground, but it ended up being a failure. And now... DirectX 12 arrives. Yes, the same DirectX 12 that we once envisioned as part of Windows 9, and that now should be introduced to the public alongside Windows 10.
One of the first details that circulated about DirectX 12 is that it will seek to work closer to "the metal", which makes us think of a behavior similar to Mantle. However, the latest bomb, if we obey internal and anonymous sources that enjoy leaking data in the corridors of Redmond, is that DirectX 12 will incorporate asynchronous multi-GPU support. In other words, a game optimized for DirectX 12 will be able to distribute the processing of each frame between Nvidia and AMD cards, without apparent restrictions. Let's see: Under normal conditions, two GPUs (or more) from the same company render frames alternately. While this increases performance, it also limits the available buffer, increases latency, and generates the damn "micro stuttering" that drives players crazy.
Under DirectX 12's wing, frame rendering would not be alternating but split, giving the developer the ability to assign, whether manually or automatically, the workload that each GPU must process in the same frame. Split frame rendering (technically Split Frame Rendering) is actually a fairly old trick, but the novelty here is that DirectX 12 will allow its application across hardware made by different companies. The potential is enormous, and another aspect to highlight is that it would not be limited to dedicated cards. Laptops with dual video, APUs and other secondary graphics systems could benefit. As always, everything will depend on how well developers take to this. We'll know more at the next GDC.
