1: get a i5 3570k as it is faster
2: get a asrock extreme4 z77 motherboard
3:get a hyper 212 evo as it cools better
4: get a 7850
For a single card setup, you only need 600W. Gold rating is good, but remember the cost to get it is probably more than the saving in your electricity. Definitely get a modular one.
for RAM, popular choice is 8GB of Corsair Vengeance 1600Mhz or its equivalent G.Skills kit.