Ok, overclocking your CPU is great, but it concentrates on CPU tasks. Graphics fall under GPU, which is the video card, or on board graphics. If it's onboard graphics, the best advice I can give you is to get a dedicated graphics card. If you already have a GPU, you can try overclocking the GPU, but if that doesn't help much, then you would need a new card. Another thing you should look into is turning down the settings on the game you're wanting to play, if you haven't already done so.
In the future though, you should add more information to your post. For instance, instead of saying "when actually play the game" specify what game so that we can inform you if there are issues related to that game.
I hope this helps!