Stop using the term 'bottleneck', it's worthless terminology. The only thing a CPU or GPU could possibly 'bottleneck' is the application you are trying to run, they don't bottleneck each other though, either they complement each other or they don't, complement is a much more effective term for describing the relationship between a CPU and a GPU, a certain CPU or GPU could complement each other and work as a team or they would they would not complement and work against each other but the term 'bottleneck' needs to washed out of the mouth and replaced with complement or compatibility. Traditionally the CPU does not offer any control of the GPU or vice versa, this has changed since the advent of the APU but you can't bottleneck another piece of hardware, either it is working in conjunction with the other components or it is not..