I would only run a minimum of 1000 watts for sli. With an 80+ psu, like http://www.newegg.com/Product/Product.aspx?Item=N82E16817171076&cm_re=1000w_power_supply-_-17-171-076-_-Product , you could run the system and still have headroom without streaching the thermals of the 750Watt psu.