GPU not using dedicated memory.

[Adeel Tariq]

I have a hp notebook with nvidia ge-force graphics card (940m 2 GB).
I know this laptop is not for gaming and i only play games which do not require high end gpu's on it.

Cause...

Recently i was playing game on it with laptop plugged in. I have set laptop performance to maximum when plugged in.
During game play my power went out and i had some stutter in my game. Usually game would recover as laptop will get power from battery but this time it didn't happen and my FPS remained low.

Problem...

I have been closely monitoring my laptop while doing graphic intensive work (usually game). During these task when i go to task manager i see GPU usage is 100% (in 3D graph of task manager), but dedicated GPU memory (2GB), only 0.4 of it is being used constantly. I verified it by using processExplorar tool as well. Due to this GPU has to render every frame again and again because it is not storing frames in GPU memory so due to repeated rendering performance (FPS) fluctuates a lot, and in some games FPS has dropped to half. i.e in CS-GO i had about 90-100 FPS (settings recommended by Ge-Force experience software) but now max FPS i get is 50 which in some conditions drops to 30 or even low. Before this problem my GPU used almost full dedicated memory for these same games with same settings.
I used GPUMemTest tool to check GPU dedicated memory. During that test in my task manager dedicated memory was almost fully used (in Compute_0 graph of task manager) and tool result was OK.

Things i tried...

I recently updated GPU drivers so i reverted back but it didn't help.
I uninstalled and reinstalled GPU drivers but didn't solve.
I completely reinstalled new windows but no solution.
I have latest GPU drivers as per recommended by Nvidia Ge-force Experience.
My games always run using high end graphics card.

So can anyone tell me what is wrong with my laptop and how can i fix it?

Thank You.