Last Fall, Nvidia released the Geforce GTX 970. It has 5.2 BILLION transistors on it. It already supports DirectX 12. Right now. It has thousands of cores in it. And with DirectX 11, I can talk to exactly 1 of them at a time.
Meanwhile, your PC might have 4, 8 or more CPU cores on it. And exactly 1 of them at a time can talk to the GPU.
Let’s take a pause here. I want you to think about that for a moment. Think about how limiting that is. Think about how limiting that has been for game developers. How long has your computer been multi-core?
But DirectX 12? In theory, all your cores can talk to the GPU simultaneously. Mantle already does this and the results are spectacular. In fact, most benchmarks that have been talked about have been understated because they seem unbelievable. I’m been part of (non-NDA) meetings where we’ve discussed having to low-ball performance gains to being “only” 40%. The reality is, as in, the real-world, non-benchmark results I’ve seen from Mantle (and presumable DirectX 12 when it’s ready) are far beyond this. The reasons are obvious.
DirectX 11: Your CPU communicates to the GPU 1 core to 1 core at a time. It is still a big boost over DirectX 9 where only 1 dedicated thread was allowed to talk to the GPU but it’s still only scratching the surface.
DirectX 12: Every core can talk to the GPU at the same time and, depending on the driver, I could theoretically start taking control and talking to all those cores.
That’s basically the difference. Oversimplified to be sure but it’s why everyone is so excited about this.
The GPU wars will really take off as each vendor will now be able to come up with some amazing tools to offload work onto GPUs.