I have decided to build a budget PC for office work. Few games and good amount of HD movie playback. I do photo shopping rarely. So I chose Gigabyte B85 D3H on budget and chose Intel core i3 4150 3.5Ghz. I have creative sound blaster 5.1 with T6100 speakers. All I need is a good performance RAM of around 4GB. For my needs, I feel 4GB is quite good. So I saw that the mobo supports 4 1.5 volts DIMM memory slots. Help me choose a RAM with the best performance. Do I need to buy two 2 GB ones or single 4 GB ram help me with it. Forgot to mention I prefer windows 7 OS.