CPU vs. GPU Rendering - What's the difference and which should you choose?
What CPU and GPU are suitable for 3D modeling and rendering? Which ones are the best out there and which ones are good enough for beginners who are getting started in 3D
Cycles detecting two of a single graphics processor - Cycles Development - Blender Developer Talk
Behind The Pixelary — CPU vs GPU rendering in Blender Cycles
cycles render engine - Images rendered on CPU and GPU are not the same - Blender Stack Exchange
CPU vs GPU Blender 3D OSX 10.11 by anul147 on DeviantArt
Use CPU and GPU when rendering with Blender Cycles - Darryl Dias
Blender 2.79: Render With GPU and CPU in Blender (+ Benchmarks) - BlenderNation
CPU vs. GPU Rendering - What's the difference and which should you choose?