Cpu vs gpu vs ram rendering in blender I have an Intel Core2Duo e7400 processor, 3 GB ram, 120G SSD hard drive, and an nVidia Geforce 750Ti 2GB graphics card. When i gpu render vast scenes of about 100MB using Cycles in Blender, I receive the CUDA out of memory error. My motherboard maximum ram support is only 4gb DDR2.

So i wants to ask if I should buy an AMD RX480 8GB graphics card, or alternatively an i7 6700k processor with 16GB RAM to work with my 750Ti graphics card. Which one will be better for rendering large images and animations?
Well, everything depends on your scene. 

An 8GB graphics cards will be faster than than your CPU but you will be limited to 8GB (side note: do not keep in your old 2GB graphics card, along with the new 8GB card, Blender will only use the ram of the lowest card) 

If you go with the CPU 16GB ram then you will be able to render larger scenes but it will be slower. 

I would say get the graphics card with 8GB.