So recently, i just bought the MSI GTX 750 TI Twin Frozr 2GB, and i researched that this card needs a 400 watt power supply and 20 amps. My computer has a 550 power supply BUT this power supply came with the computer, so i dont really know if i can trust the power supply. But this powersupply has 42amps on the +12v rail. will this gpu run?