What is GPU rendering?
GPU rendering means, that there is used the power of GPU (Graphics processing unit / Graphics card) for rendering, instead of CPU (processor). GPU is much more powerfull in these days than CPU and the future will belong to GPU for sure.
Is there important GPU memory for rendering?
Yes, the GPU memory is MORE imporant than GPU speed. When you are using GPU for rendering, you have to got all into GPU memory. With low memory your render will crash. GPU memory is THE MOST IMPORTANT for rendering.
Is there imporant CPU speed and system memory?
There is imporant to have no so much slow computer for GPU rendering, because you will use CPU for compile GPU effect and some process, but it's NOT essential for the rendering speed. The most imporatnt is GPU speed and GPU memory.
NVIDIA or ATI (AMD)
Almost all advanced GPU renderes like FurryBall, Octane, iRay - support NVIDIA (CUDA) only for the raytrace. So there is much bettter to buy NVIDIA card for sure.
How fast is GPU rendering?
We are preparing our own tests, but according this tests - it's about 15x - 100x faster on single GPU, than i7 CPU processor.
Cuda or OpenCL in 2014?
Everything that's possible in CUDA is also possible in OpenCL (but more difficult)
For as long as we're not using libraries, a given task is not significantly easier (or more difficult) to do in either of them
CUDA's main advantage is the availability of libraries
Both have good support for all three main platforms (Win/OSX/Linux)
CUDA is much easier and better supported.