hi i dont actually know how much amps my psu hav
but here are the details
switching power supply
model ATX 400w
ac input : Voltage 230V current 5A Frequency 50hz
dc output max: orange 3.3v and 18A ,Red +5, 18A , Yellow +12V , 20A, White -5v .05A,Blue +12V,03A,purple 5V,2A,grey P/G, OK
so will this be okay to run r7 250x or do i need to change it plz rply??????