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My mac is a macbook pro 2017, with AMD Radeon Pro 560.

Seeing this question How to do GPU rendering on MacBook Pro 2016 (AMD Radeon Pro 460) I also get the Cycles render to work, but it renders at slower speeds than the CPU, an intel core i7 2.8ghz.

I have set the render settings in Preferences to OpenCL, and the Scene device settings to GPU Compute. It still takes nearly 3 secs to render all 32 steps with the startup cube just set to Rendered View.

CPU settings: 1.07 sec GPU settings: 2.82 sec

Is this just AMD not being implemented for macOS or is the Radeon Pro 560 not so Pro after all?

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  • $\begingroup$ What leads you to believe performance should be better? What reference are you comparing to? Your card is probably midrange and your OS choice is very unfriendly for high performance work $\endgroup$ – Duarte Farrajota Ramos Jul 3 '18 at 11:42
  • $\begingroup$ Based on my previous experience with GPUs, they always increase the speed in Cycles, but that experience is based on Nvidia GPUs. So I thought that also OpenCL on AMD should manage to increase the render speed. $\endgroup$ – chrleon Jul 3 '18 at 17:47
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Actually there is one more thing you should do before trying GPU render, that GREATLY affects the render speed: the size of the render tile. By default, render tile in Blender is fairly small which works well for CPU-based rendering. However GPU renderers work faster with large render tiles, around 512px (default is 64px I think). See this article for details, step 3: https://www.blenderguru.com/articles/4-easy-ways-to-speed-up-cycles

The tile size parameter:

enter image description here

Comparison tile size vs render speed: enter image description here

Since I am interested in Macbook Pro performance, can you check the tile size again and post your results?

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  • $\begingroup$ Thanks. No difference at all. Intel CPU still faster. Startup scene rendered at 1920x1080. GPU tilesize 256: 5:11 sec. CPU tilesize 32: 3:12 sec. $\endgroup$ – chrleon Aug 20 '18 at 10:52
  • $\begingroup$ Oh man, this is a bummer, as I am looking into getting the new MBP 15, and hoped that AMD GPU can at least edge out CPU a bit. If you change the tile size, how that affects the GPU render times? I know on my Alienware when I used small tile size for GPU rendering it was slower than CPU, but when I increased to 512px, it went on to render about 4-8x faster than CPU. Of course it's the GTX1060 card, but still... $\endgroup$ – Neko Aug 20 '18 at 13:51
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Agree. Blender 2.79 with OpenCl. Activated it in user preferences. The AMD card was shown and selected. Running benchmarks varying block sizes from 8x8 to 512x512 showed that my mid 2015 MBP cpu is way faster. I have the Radeon 2gB card. My only guess is that the driver needs optimization or the 2gB is an issue.

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