Star Swarm, DirectX 12 AMD APU Performance Preview

After several requests and a week’s break from our initial DirectX 12 article, we’re back again with an investigation into Star Swarm DirectX 12 performance scaling on AMD APUs. As our initial article was run on various Intel CPU configurations, this time we’re going to take a look at how performance scales on AMD’s Kaveri APUs, including whether DX12 is much help for the iGPU, and if it can help equalize the single-threaded performance gap been Kaveri and Intel’s Core i3 family.
 
To keep things simple, this time we’re running everything on either the iGPU or a GeForce GTX 770. Last week we saw how quickly the GPU becomes the bottleneck under Star Swarm when using the DirectX 12 rendering path, and how difficult it is to shift that back to the CPU. And as a reminder, this is an early driver on an early OS running an early DirectX 12 application, so everything here is subject to change.
 
CPU:AMD A10-7800
AMD A8-7600
Motherboard:GIGABYTE F2A88X-UP4
Power Supply:Rosewill Silent Night 500W Platinum
Hard Disk:OCZ Vertex 3 256GB OS SSD
Memory:G.Skill 4x4GB DDR3-1866 9-10-9 F3-14900CL9Q-16GBXL
Video Cards:MSI GTX 770 Lightning
AMD APU iGPU
Video Drivers:NVIDIA Release 349.56 Beta
AMD Catalyst 15.200 Beta
OS:Windows 10 Technical Preview 2 (Build 9926)
 
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To get right down to business then, are AMD’s APUs able to shift the performance bottleneck on to the GPU under DirectX 12? The short answer is yes. Highlighting just how bad the single-threaded performance disparity between Intel and AMD can be under DirectX 11, what is a clear 50%+ lead for the Core i3 with Extreme and Mid qualities becomes a dead heat as all 3 CPUs are able to keep the GPU fully fed. DirectX 12 provides just the kick that the AMD APU setups need to overcome DirectX 11’s CPU submission bottleneck and push it on to the GPU. Consequently at Extreme quality we see a 64% performance increase for the Core i3, but a 170%+ performance increase for the AMD APUs.
 
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