ATI Powerplay question

I have Asus N61JQ, and I notice the GPU Core/Memory clock stuck at 300/300 when Powerplay is enabled in ATI Catalyst with Maximum Battery LIfe setting, and the core/memory clock would not ramp up to the original 650/800 even under 3D.
When I choose Powerplay enabled with Maximum Performance Setting, the Core/Memory would run 650/800 all the time, and would not reduce to 2D speed of 300/300. Is this normal ?

I thought ATI Powerplay would switch to 2D or 3D clock automatically depending on GPU load, but this is not happening in my case.
I tried several drivers, like 10.7, 12.1, & 13.4, but it is always the same. I have to manually enable / disable PowerPlay (or manually choose Maximum Performance or Maximum Battery Life with Powerplay enabled) to switch GPU core/memory clock from 2D to 3D speed.