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Tested: DirectX 12's potential performance leap is insane

Gordon Mah Ung | March 27, 2015
We already know DirectX 12 will drastically improve game performance when Windows 10 ships later this year, but just how much of a "free" boost you'll get isn't exactly known.

Although it's difficult to actually say which actual API was developed first (I've read stories that said DirectX 12 has been in the works for numerous years, while others report AMD was likely the first to push it), this test at least shows the potential of both of the new APIs. DirectX 12, in fact, is even slightly more efficient, cranking out 13.4 million draw calls per second.

The whole Mantle vs. DirectX debate is over anyway, as AMD itself has encouraged developers to use DirectX 12 or Vulkan, OpenGL's gaming-focused successor, instead.

Remember that part where I said that Futuremark says not to use this as a GPU test? You still want to see to see this on Nvidia hardware, so I repeated the above test with the GeForce GTX Titan X in the R9 290X's place. There's no Mantle, of course, since that's an AMD-only feature.

You're also going to be curious about DX12's impact on integrated graphics processors (IGP). With Intel's graphics actually in use by more "gamers" than AMD and Nvidia's discrete cards, it's a valid question, but I'll be honest: Gaming with IGP ain't real gaming. I didn't see the point in running tests on Intel's IGP.

Fortunately, Microsoft provided results from its own IGP machine using a Core i7-4770R "Crystal Well" CPU with Intel Iris Pro 5200 graphics. The quad-core chip is used in high-end all-In-ones and Gigabyte's Brix Pro. That's pretty much the very best performance you can get out of an Intel chip today, and here are the results.

Not bad — until you glance back at the AMD and Nvidia charts above. 

But remember that DirectX 12 is about making the API more efficient so it can take better advantage of multi-core CPUs. It's not really about graphics cards. It's about exploiting more performance from CPUs so they don't bottleneck the GPU.

With that in mind, I decided to see how the CPU can change the results, by varying the core and thread count as well as clock speeds in various configurations. I limited the quad-core Core i7-4770K to two cores, switched Hyper-Threading on and off, and limited the clock speeds the CPU could run at.

The big winner was the Core i7-4770K set to its default state: four cores and Hyper-Threading on. All of the tests were conducted with the GeForce GTX Titan X card. I'm only comparing the DirectX 12 performance because that's all that matters here.

Which CPU is best for DirectX 12?

To make this a little easier to understand from a system-buying or -building perspective, I also tried mimicking the different clock, core count and Hyper-Threading states of various Intel CPUs. (If you want to dig into the details of the chips I tried to simulate, I've lined up the details over at Intel's ARK.) 

 

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