Enhanced G51j Vs Black Ops

Hello,
I got the new asus g51j with following specefications:

- Geoforce GTS 360, CUDA VRAM 1GB (Nvidia GPU)
- Memory 8G
- Intel core i7-720M
- EAX Advanced HD 4.0
- HDD 640G
- ODD 4x Blue Ray

Also I bought COD Black Ops. When the power plugged in the gameplay for MP/SP is so smooth and i can play it with highest graphic settings. Sometimes I need to play it on battery mode but I face an annoying lag with the graphic. The lag is too bad that you can't predict the mouse movement.

I tried to overlock the GPU + CPU but the same problem is exist. I didn't try the undervolting. I tried to play on power mode without overclocking the cpu (Power4gear app was not setup to turbo or extreme turbo mode) but still I can play the game online or offline without any problem.

My questions now:
Do you face the same problem while using battery mode?
what is the real problem causing this lag in battery mode ?
Is there any chance to resolve it?

Regards

 

It's nvidia powermizer downclocking, no way around it. Don't play on battery, really.

 

Thanks for the fast answer, it is really sad to know that. I bought this device to be a mobile gaming mechine but I have to stick to the power supply.

Anyways could anybody list the factors to increase FPS ?

regards