I have a work computer a friend of mine gave me that has a generic turbolink 500w power supply with 18 amps and some decent specs which i want to install a gtx evga 750 ti SC, now i know the evga superclocked 750 ti requires a 20 amp psu but im just wondering if the 18 amp is enough. If not then im obviously gonna upgrade to a official brand with the required amps.