Fans use about 3 watts each and don't matter. Nvidia recommends an 800w power supply for GTX 680 Sli. That assumes a junk brand power supply. Even factoring in overclocking a quality 800w power supply will be fine for your listed system.
http://www.realhardtechx.com/index_archivos/Page362.htm
Stick with Corsair, Seasonic, PC Power and Cooling, XFX, Silverstone, Enermax, OCZ and Antec for quality.
Here are some excellent models.
http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=100007657%20600014024&IsNodeId=1&bop=And&CompareItemList=58%7C17%2D371%2D050%5E17%2D371%2D050%2DTS%2C17%2D139%2D022%5E17%2D139%2D022%2DTS%2C17%2D207%2D017%5E17%2D207%2D017%2DTS%2C17%2D341%2D044%5E17%2D341%2D044%2DTS%2C17%2D151%2D102%5E17%2D151%2D102%2DTS