Building computer for a friend, fx 8300, r9 280x, evga 600w psu with 49 amps on a 12v rail, will the psu support this setup? My main concern is the 280x
It will work and provide enough power, but the power supply is not high quality and could fail soon.
Also you have selected very power hungry components for just average performance. i5-4460 + GTX 960 will cost about the same, perform about equally or better yet It's much more efficient and only requires a (good quality) 400-450 watts PSU.