HOW MUCH SHOULD THIS MATTER TO YOU?
But if all DirectX 12 cards will get to enjoy the advantages of the underlying API, does that mean that feature level support is inconsequential? That depends.
The Fiji GPU on AMD's flagship Radeon R9 Fury X uses the latest Graphics Core Next (GCN) 1.2 architecture and supports DirectX feature level 12_0. On the other hand, top NVIDIA cards using the GM200 GPU like the GeForce GTX TITAN X and 980 Ti support feature level 12_1.
One edge that NVIDIA has is support for conservative rasterization with feature level 12_1. Shadows are one of the more difficult things to render in a true-to-life manner, but conservative rasterization enables smoother and more natural shadows, which is something that will be readily observed by end users.
On the other hand, AMD's GCN 1.2 architecture supports Resource Binding Tier 3, which – thanks to some backend changes that don't require the CPU to work as hard – improves performance and makes for a more efficient graphics pipeline. However, unlike conservative rasterization, these changes don't translate into any on-screen eye candy, so NVIDIA may in fact have the advantage here, at least in terms of perceivable benefits.
But let's return to the example of the Radeon R7 370. The card only supports feature level 11_1, whereas the NVIDIA GeForce GTX 950 supports feature level 12_1. In the world of product marketing – where facts are often blurred – this has led to claims that AMD cards, including GCN 1.2 cards such as the Radeon R9 Fury X, don't fully support DirectX 12.
This is slightly misleading, because no single graphics card supports the entire set of DirectX features. For instance, the NVIDIA GeForce GTX TITAN X and 980 Ti only support Resource Binding Tier 2 (compared to Tier 3 on AMD's GCN 1.2 cards), despite their much-vaunted feature level 12_1 support.
At the end of the day, there's just one key takeaway: full support for DirectX 12 is a myth. Each card from NVIDIA and AMD both support different feature sets, and it's up to you to decide which matter more, or if at all.
Regardless of whether they support feature level 12_0 or 12_1, no one card supports the entire set of DirectX 12 features.
Figure 8: Regular Shadow Map
Conservative rasterization allows for more natural shadows.
Figure 9: Ray Traced - Conservative