It should work just fine, math-wise. CPU runs 88W officially [in reality, You can go from 70-80 max with non OC up to 110W with some general OC. My non-OCed 4790K is refusing to eat more than 74Watt, which is weird, but who gives, right?]. And maximum GTX 970 consumption should peak somewhere around 170 Watt. So 2 x 170 Watt graphics cards + let's say 110 watt cpu + mobo 25 - 80 Watt [high end eat up to 80 watt] + ram [if You have two modules it's 6 watt, if 4, it's 12 watt] + hdd/ssd [let's say 20 watt, and that's too much, since SSD eats zip, and HDD 4-10 watts], means Your system can peak somewhere around 530 Watt, with some heavy cpu OC, and 570 Watt tops with some VGA OC. Rails are solid enough to run SLi too. I myself would get 750 Watt psu, but this 650 Watt should do just fine...