How many watts should I get for my system which will have a i5-4670k, and evga gtx 770 (2 of them in sli)? And if it matters I am not going to overclock what so ever. I was looking at the EVGA SuperNOVA NEX 750g power supply it has 80 plus gold with 750 watts, will that be enough? and if not please recommend some psu's ( i would like if they were full modular).