AMD overdrive settings.

I recently got a Radeon HD 7950 and was wondering about the overdrive settings, it says "Clock settings are applied only when the GPU is running in high performance mode." I was wondering if there is a way to control the overdrive when I need it. Now I do understand it does this on its own but for some reason the particular game I'm playing (spoutcraft) it doesn't want to use overdrive. And funny enough, the gpu clock goes to 300mhz when I'm moving in the game but then it clocks to 775mhz when I'm idlel. So its kinda not doing its job at all, rather the exact opposite. So basically just wondering if there's like some manual control for the overdrive.

Oh and I'm also overclocking my cpu at 4,600