Are you talking about the 670 graphics card? If so yes you should have plenty of power for that with a 750 watt! You really only need better if you are gonna do dual SLI.
I just looked up that specific model, it looks like it takes 170 watts of power peaked (but I could be wrong but I seen in on multiple sites). But you should still be fine either way. Your friends PC should be okay as well with 750 watts.
Shoot, I am running 2 560ti's in SLI, 3 hard drives, and Passport backup drive, 4 case fans with lighting, and 2 dvd drives in my build on a 750 watt Corsair PSU, and all has been working perfectly for over a year.