what ddr3 ram should i get?
For general computing and gaming, 8GB of RAM is the sweet spot. Get a set of two 4GB DDR3 DIMMs, at at least 1600MHz. If you're running AMD's Trinity platform, you should get DDR3/1866, but DDR3/2133 is a good step up if you can afford it. If you're on Ivy Bridge or Haswell, DDR3/1866 is a good step up.