Both scenarios the cable is plugged into power adapter that was included with the 5s. Using non-genuine cable - 5s will display a warning something like, "This cable may not be compatible". When I used it with my old iPhone 5 with iOS 6, it did not display that message. It appears iOS 7 on the new iPhone 5s can identify the non-genuine cables. - Will still charge the phone despite the fact of displaying the warning. - Also, the cable will not transfer or charge when plugged into a PC USB port (or MAC USB port) Using genuine apple cable - The phone charges slightly faster. For example, after 5 minutes it will charge 3% where as the non-genuine cable will be between 1-2%.