Agree with what others have said. Your motherboard is not good enough to overclock with, your cooler is not good enough, and even if you had a 990fx board and hyper 212 evo cooler you would still not be able to overclock the 6300 to not bottleneck a 970.
Now people often overexagerate bottlenecking as a serrious problem. Lets say a 960 is 65% of the performance of a 970, and lets say that your CPU can only use 80% of the 970's performance, you are still getting better performance with the 970 then you are with a weaker GPU; and this example is only for the CPU intensive games, GPU intensive games will be able to use all of your 970 GPU. Now if you had say a fx4300 or a10 then yeah your CPU would bottleneck the 970 so much that you would see almost no performance difference between the 960 and 970.