You don't need a 1000W power supply unless you're going SLI or Crossfire with graphics cards. In fact, most PSUs are inefficient until you use like 60%. What you want is a good brand of power supply like Seasonic or Corsair. An important thing is its efficiency, which are 80 plus, bronze, silver, gold, and platinum. You can tell which is best. The number of watts you should get is whatever your graphics card says is the minimum. For example, the GTX 770 has a minimum of 600W power supply.