I'm asking this theoretical question because obviously I haven't tried it. Is 4 GPU's of 4 GB better than 2 GPU's of 8GB specifically for Blender rendering in Cycles since the app allocates a tile to each GPU in the process? Did anyone experimented or knows which combination is faster given that the motheboard, CPU and memory can handle both of them? TY
"Better" is not the question... it is the wrong word to use, as it depends.
4 GPUs will render 4 tiles simultaneously so rendering an image will be faster than with 2.
Memory: GPUs cannot share vRAM, once you hit the limit the GPU will fail.
So it all depends on the complexity of the scene you are trying to render, or how long can you wait for the render to be done.