Power problem with alienware M18x

Hey there, someone please help me... My M18x alienware have some power problem I think... I turned it on and it's working as if I was not using a 180W power source and stays in low performace, its the same power source I aways used, the one that came together with the notebook. Even through the battery is charging and here it says its plugged the computer is not working full performance. when i hit the I/D GFX button in the keyboard it tells me I need to reboot so the problem is solved, but when I do it, it starts all the same. I dont know what to do anymore, please help me.