Exploring DirectX 12: 3DMark API Overhead Feature Testby Ryan Smith & Ian Cutress on March 27, 2015 8:00 AM EST
Before jumping into our results, let’s quickly talk about testing.
For our test we are using the latest version of the Windows 10 technical preview – build 10041 – and the latest drivers from AMD, Intel, and NVIDIA. In fact for testing DirectX 12 these latest packages are the minimum versions that the test supports. Meanwhile 3DMark does of course also run on Windows Vista and later, however on Windows Vista/7/8 only the DirectX 11 and Mantle tests are available since those are the only APIs available.
From a test reliability standpoint the API Overhead Feature Test (or as we’ll call it from now, AOFT) is generally reliable under DirectX 12 and Mantle, however we would like to note that we have found it to be somewhat unreliable under DirectX 11. DirectX 11 scores have varied widely at times, and we’ve seen one configuration flip between 1.4 million draw calls per second and 1.9 million draw calls per second based on indeterminable factors.
Our best guess right now is that the variability comes from the much greater overhead of DirectX 11, and consequently all of the work that the API, video drivers, and OS are all undertaking in the background. Consequently the DirectX 11 results are good enough for what the AOFT has set out to do – showcase just how much incredibly faster DX12 and Mantle are – but it has a much higher degree of variability than our standard tests and should be treated accordingly.
Meanwhile Futuremark for their part is looking to make it clear that this is first and foremost a test to showcase API differences, and is not a hardware test designed to showcase how different components perform.
The purpose of the test is to compare API performance on a single system. It should not be used to compare component performance across different systems. Specifically, this test should not be used to compare graphics cards, since the benefit of reducing API overhead is greatest in situations where the CPU is the limiting factor.
We have of course gone and benchmarked a number of configurations to showcase how they benefit from DirectX 12 and/or Mantle, however as per Futuremark’s guidelines we are not looking to directly compare video cards. Especially since we’re often hitting the throughput limits of the command processor, something a real-world task would not suffer from.
Moving on, we also want to quickly point out the clearly beta state of the current WDDM 2.0 drivers. Of note, the DX11 results with NVIDIA’s 349.90 driver are notably lower than the results with their WDDM 1.3 driver, showing much greater variability. Meanwhile AMD’s drivers have stability issues, with our dGPU testbed locking up a couple of different times. So these drivers are clearly not at production status.
|DirectX 12 Support Status|
|Current Status||Supported At Launch|
|AMD GCN 1.2 (285)||Working||Yes|
|AMD GCN 1.1 (290/260 Series)||Working||Yes|
|AMD GCN 1.0 (7000/200 Series)||Working||Yes|
|NVIDIA Maxwell 2 (900 Series)||Working||Yes|
|NVIDIA Maxwell 1 (750 Series)||Working||Yes|
|NVIDIA Kepler (600/700 Series)||Working||Yes|
|NVIDIA Fermi (400/500 Series)||Not Active||Yes|
|Intel Gen 7.5 (Haswell)||Working||Yes|
|Intel Gen 8 (Broadwell)||Working||Yes|
And on that note, it should be noted that the OS and drivers are all still in development. So performance results are subject to change as Windows 10 and the WDDM 2.0 drivers get closer to finalization.
One bit of good news is that DirectX 12 support on AMD GCN 1.0 cards is up and running here, as opposed to the issues we ran into last month with Star Swarm. So other than NVIDIA’s Fermi cards, which aren’t turned on in beta drivers, we have the ability to test all of the major x86-paired GPU architectures that support DirectX 12.
For our actual testing, we’ve broken down our testing for dGPUs and for iGPUs. Given the vast performance difference between the two and the fact that the CPU and GPU are bound together in the latter, this helps to better control for relative performance.
On the dGPU side we are largely reusing our Star Swarm test configuration, meaning we’re testing the full range of working DX12-capable GPU architectures across a range of CPU configurations.
|DirectX 12 Preview dGPU Testing CPU Configurations (i7-4960X)|
|6C/12T @ 4.2GHz||Overclocked Core i7|
|4C/4T @ 3.8GHz||Core i5-4670K|
|2C/4T @ 3.8GHz||Core i3-4370|
Meanwhile on the iGPU side we have a range of Haswell and Kaveri processors from Intel and AMD respectively.
|CPU:||Intel Core i7-4960X @ 4.2GHz|
|Motherboard:||ASRock Fatal1ty X79 Professional|
|Power Supply:||Corsair AX1200i|
|Hard Disk:||Samsung SSD 840 EVO (750GB)|
|Memory:||G.Skill RipjawZ DDR3-1866 4 x 8GB (9-10-9-26)|
|Case:||NZXT Phantom 630 Windowed Edition|
|Video Cards:||AMD Radeon R9 290X
AMD Radeon R9 285
AMD Radeon HD 7970
NVIDIA GeForce GTX 980
NVIDIA GeForce GTX 750 Ti
NVIDIA GeForce GTX 680
|Video Drivers:||NVIDIA Release 349.90 Beta
AMD Catalyst 15.200.1012.2 Beta
|OS:||Windows 10 Technical Preview (Build 10041)|
Intel Core i7-4790K
Intel Core i5-4690
Intel Core i3-4360
Intel Core i3-4130T
|Motherboard:||GIGABYTE F2A88X-UP4 for AMD
ASUS Maximus VII Impact for Intel LGA-1150
Zotac ZBOX EI750 Plus for Intel BGA
|Power Supply:||Rosewill Silent Night 500W Platinum|
|Hard Disk:||OCZ Vertex 3 256GB OS SSD|
|Memory:||G.Skill 2x4GB DDR3-2133 9-11-10 for AMD
G.Skill 2x4GB DDR3-1866 9-10-9 at 1600 for Intel
|Video Cards:||AMD APU Integrated
Intel CPU Integrated
|Video Drivers:||AMD Catalyst 15.200.1012.2 Beta
Intel Driver Version 10.18.15.4124
|OS:||Windows 10 Technical Preview (Build 10041)|