Overclocking: Why does minecraft not exceed GPU Stock speeds?

I have overclocked my GPU (Nvidia GTX 650 Ti Boost) up 50Mhz using gigabyte OC guru II. When i preform a test, the clock speeds are as they should be, but when i run minecraft(tekkit), it does not exceed the stock speed of 980Mhz. Can anyone help?

If you haven't been checking before then it might've never gone above stock speeds when playing minecraft. Minecraft isn't a demanding game at all so I wouldn't be surprised if this were the case.