iray can be set to use the available GPUs, CPUs or a hybrid mode which utilizes both types of processors simultaneously. However, iray is optimized for CUDA enabled GPUs and the highest performance is achieved by using these GPUs.
The exact GPU hardware specifications vary with content and application requirements. While all CUDA-enabled GPUs are supported, average scene size requirements for professional users will make NVIDIA Quadro®, QuadroPlex® and Tesla® systems for workstations as well as Tesla server units the platforms of choice.
Reccommended NVIDIA Graphics Processing Units (GPUs)
To learn more about application specific GPU configurations that are right for you, please see the following: