Hi, I want to upgrade the RAM on my MacBook Pro Mid 2012. Would it be possible just to buy a 4GB stick and take out a 2GB stick in it's place? This would leave me with 6GB RAM and would mean having uneven amounts of RAM. The reason I need extra RAM is for gaming, so is it possible/worth it to get an additional 4GB of RAM and have uneven amounts of RAM installed, while still seeing a performance increase? Thanks in advance!