It all depends on how much game the game or games actually demand and use. Example: If I'm playing Minecraft and it's only using 2GB/4GB , then I upgrade to 8GB of ram, I wouldn't notice the difference because it's still using that 2GB out of 8GB available ram. But lets say I'm playing Battlefield 4 and it's using 4GB/4GB ram although the game is supposed to be running with 6GB of ram, as well as lagging trying to multitask and do other variances, then yes a impact would be noticeable, given 6GB/8GB is being used. A game will only use as much ram as it needs or that it is allowed to use (manual input). Even if I have 128GB of RAM and I'm playing minecraft, it still will only use as much as it needs at any given time.