Welcome to the forums.
 
See: What is the rating for my PSU wall cable? in the EVGA FAQs.
 
You should get an AC power cable that's marked 18 AWG or lower..The lower the AWG number, the thicker the wires are in the cable..Do not get a cable with a higher AWG number that has thinner wires in the cable.
 
The C13/C14 (3-prong) input connectors are industry standard..The end that plugs into the wall can be different, depending on the voltage in the world region.
 
An EVGA 750W G2 will auto-detect the AC input voltage and auto-switch to using it like all their PSUs and the vast majority of other brands these days.
 
AC input cables can be found most anywhere PC parts/accessories are sold, even some supermarkets.
 
Using another/proper AC input cable will not void the warranty.
 
Hope that helps.

bob16314
 
You should get an AC power cable that's marked 18 AWG or lower..The lower the AWG number, the thicker the wires are in the cable..Do not get a cable with a higher AWG number that has thinner wires in the cable.
 

An 18 AWG cable is a little marginal if you are pushing that power supply hard - I've had one DIE on a machine that was pulling 700 watts at the wall 24/7 (luckily it didn't take the PS or machine with it).
18 AWG should be fine if you're not pushing the PS that hard on a continuous basis, but I'd go with at least a 16 AWG cable (which is what EVGA provides with the 850 G2 - I don't have any 750 G2 models to check) if you are going to be pushing the PS hard for extended periods.