It depends on what you would use them for. Bottlenecking only really occurs between the motherboard and another component or two different drives (a HDD and a SSD for example) The GPU and CPU are used for entirely different tasks, so they do not bottleneck each other. They are bottlenecked by whatever you are using them for.
Think of it this way:
If your CPU and GPU are on the same highway, they would both be in a different lane but never cross. Now let's say you turn on a game. Now a truck is in front of the GPU slowing it down but the CPU doesn't have anything holding it back so it just keeps going. Then you turn on streaming while you are gaming and now there's a truck in front of the CPU too.
Now to answer your question on...