Bottlenecking will not damage any parts, however, if the CPU is not fast enough, it will not be as effective at running the game as a CPU that can. A 970 on a dual core 2.8GHz processor will have less frames per second as a quad core 3.2GHz, because the information the graphics card is being sent is only as fast as the speed of the processor. If the graphics card can handle, say, 3.5GHz, a 2.8GHz processor would leave the graphics card running at approximately 70% load, which isn't using as much resources as it could be.