Same problem here as well. Been years since I made a pc and just making one now. Thing is I have got a i5 3570k , gigabyte gtx 670 wind force oc and 8gb ram. Because within these last few weeks I have learnt a lot so found that the 750w psu I have is dual rail but 22amps each. I have look into it and I know the card is 170w which is 15amp so you would think it would be ok. But I'm have doubts.
Like I said I'm new at this. I think the psu is an ACE psu