Thank you all guys for your help.
Chuck you are right, it has that U at the end of its name. Its i7-7500U 2.7Ghz.
Prime _Evil, I tried your solution but it didn't work.. Thanks for helping anyway.
Iwansquall, I thought that the machine was changing to my NVidia GeForce by itself when playing the game, but it turns out its not. But the most annoying thing, is that even if I added D2SE.exe and GAME.exe to use my graphic card, when playing I check and the graphic card is inactive..
I tried to add DiabloII.exe in graphic card list too, but its not letting me..
(Changed power setting to high performance also.)