Microsoft could be on the verge of a graphics card breakthrough with the arrival of DirectX 12, as the new API will allow PC users to combine GPUs from different manufacturers.

Presently, PC users who want to double the number of graphics cards attached to their motherboard are restricted by the manufacturer. So, two Nvidia GeForce cards of the same type would work via SLI, and two AMD Radeon cards can unite via Crossfire, but these cannot be mixed and matched.

However, Microsoft is preparing a major announcement at the Games Developers Conference, where it is expected to explain that DX12 can combine all the different graphics resources in a system and treat them as though they were a single card.

The rumour first emerged on Tom's Hardware earlier this week. A source connected to the matter, who asked not to be named, has since explained to GameSpot that the feature is genuine.

Microsoft is already preparing to bring many of its Xbox One games to PC

Key to the new process is how DirectX 12 will bind multiple GPUs together. According to Tom's Hardware, the tech then "treats the entire graphics subsystem as a single, more powerful graphics card. Thus, users get the robustness of a running a single GPU, but with multiple graphics cards."

Such a breakthrough could bring about new levels of convenience for PC enthusiasts and developers alike. For the first time, it will also mean that multiple GPUs can pool their memory. In theory, this means that installing two 2GB GPUs into a system will get the end user a useable 4GB of memory, unlike the current system, which would only give a user 2GB of memory.

Tom's Hardware notes that the API includes a "frame rendering method called SFR, which stands for Split Frame Rendering."

It explains: "Developers will be able to manually, or automatically, divide the texture and geometry data between the GPUs, and all of the GPUs can then work together to work on each frame. Each GPU will then work on a specific portion of the screen, with the number of portions being equivalent to the number of GPUs installed."

AMD's Mantle API, which similarly sits much closer to the hardware than DirectX 11, already allows for this feature, with Civilization: Beyond Earth being one of the most recent games to make use of it. Speaking to GameSpot, AMD's Game Scientist Richard Huddy confirmed that it's "possible" this technology can significantly reduce latency and allow for the pooling of memory, but emphasised that the onus is on developers to make use of it.

Microsoft first announced DirectX 12 in January during its Windows 10 media briefing. At the time, it surprised onlookers by suggesting that new graphics cards may not be necessary to take advantage of the API. This dual-GPU feature appears to explain why older cards could perform capably.