i dont have to convince bro. u can use dual monitor to verify it sa task manager while the game is on OR google it lang. cod4 is an example of 3D game which requires tremendous amount of computing power and will utilize your GPU 100% espcially when you are engaging or moving a lot or there is alot to process like smoke, gunfire, etc.. and ang cpu will be just below 50% BUT depende sad sa setup sa whole system nimo... most of the work sa gpu gyud..
ps. dili accurate mag measure sa cpu load sa games if windowed mode ang game kailangan full screen. but i dunno i just work here.. now back to sweeping the floor and mopping :P