Microsoft has posted a note on MSDN that DX12 will now have variable shading rate capability added. The idea is use the GPU more effectively.
For each pixel in a screen, shaders are called to calculate the color this pixel should be. Shading rate refers to the resolution at which these shaders are called (which is different from the overall screen resolution). A higher shading rate means more visual fidelity, but more GPU cost; a lower shading rate means the opposite: lower visual fidelity that comes at a lower GPU cost.
The net result is about 10-20% better frame rates. Results will vary depending on the game and the resolution of the LCD.
With the DirectX team, Microsoft wants to make sure that our features work on as much of their partners’ hardware as possible. VRS support exists today on in-market NVIDIA hardware and on upcoming Intel hardware. AMD will support this with their hardware as well.
By standardizing the VSR will make it easier for developers.