The current version of After Effects (13.7.1 on Windows 13.7.2 on Mac) does not use the GPU to accelerate much at all.
Unless you're using the obsolete ray-traced renderer to create 3d geometry or you're using some third-party plugin that renders on the GPU (Red Giant Universe, Element 3d, ShapeShifter, etc.), the GPU is going to sit there doing mostly nothing in AE.
If you are using the old ray-traced renderer, I would recommend against it; there is a much more powerful way to do 3d in AE - but you can use that GPU to accelerate the ray-traced renderer if you do want to create geometry with it for some reason.
The new version of After Effects (that is coming out "soon") does include the ability for the GPU to accelerate some native effects, but not many from what I gather. Check out the sneak peek videos or the NAB presentation videos to see that in action.
please help me i didn't get it !
Let me try again.
Are you using the ray-traced renderer?
Are you using third-party plugins? (And, if so, which ones?)
If the answer is no to both questions, then the version of AE you're using will not use the GPU to accelerate anything. So there is no problem other than your expectations.