Hello, I am building a PC for the first time and I'm really confused on what wattage psu I should get. I plan on installing a ASrock n68-gs4 motherboard, amd fx-6300 cpu, and 4 gb ddr3 ram in a Rosewill RANGER-M case. I am also confused as to what gpu I should buy, I don't want the top of the line most expensive one, just one that can run games on low graphics settings at least. Thanks, Josh.