Can blender render on multiple graphics cards? I have a PC which has 2 CPU's in the mainboard, 40 GB RAM and 3 Graphics Cards. Can Blender render for example one frame on all gpus at the same time?
And generally: is it possible to render on cpu and gpu at the same time?
Yes.
Blender's Cycles can use multiple CPUs and GPUs for rendering. You can use both CPU and GPU devices at the same time as well.