No, the overclock would only help your performance. To test any sort of bottleneck between the CPU & GPU...
-If lowering the graphics settings has no effect on frame rates, then the bottleneck is your CPU.
-If lowering the graphics settings increases the frame rate, then your GPU is reaching its upper limits.
TBH though at 1080P or something close to this res the system is well paired and you should have no issues.