As of the 6xx / 7xxx series graphics card, the power consumption has dropped significantly.
Guru3D:
http://www.guru3d.com/article/geforc...y-sli-review/4
GTX 580 tri-sli = 736 Watt
GTX 680 tri-sli = 509 Watt
The large 1200Watt and even the 1KW power supplies are simply no longer needed by the average builder. And if you build something that requires 1KW+, trust me, you will know if you need it or not.
So save yourself the money, buy a PSU with a lower wattage rating, i would even dare to say that 500W is enough for a single card setup. I ran my 470 (which require more power than any single card setup from the 28NM generation) on a 500W PSU with the i5-2500k, 3 HDDs and 2 RAM modules.
Look at this:
http://www.newegg.com/Product/Produc...82E16817371054
Perfectly viable for all setups with only 1 graphics card from the 600/7000 series of GPUs.