Say if i have a 1gb vram card and a game im playing will go unstable after 30 npcs appears on screen. Does this mean that if i switch to a 3gb vram card, i could reach 90 npcs before going unstable since 3=3 times the amount of 1?
no, you would also need more processing power in the gpu. Not just memory. The idea of a 4GB card being better than a 2GB card is marketing bull. Some 4GB cards are better than some 2GB cards, but that depends upon the card.