The S5 does not use 750W as such, it is good to have a PSU which can provide more than what the S5 needs, but you should count on around 590 - 600 watts if you run it on default (350).
can you show me the right PSU for antiminer s5...
650W should be fine. Although I would prefer 750W just to be safe. Most people I know run 2 S5s on 1300W.