You're fine:
a) That card does not require an external power connector meaning it uses under 75W, and
b) A typical GTX650 uses 64W (from NVidia site)
That 20A data is completely incorrect. The card uses less than 75W which would mean less than 6.25Amps. (Wattage = Volts X Amps)
Your data possibly means 20Amps for the CPU and the Graphics Card, but since that leaves you over 150Watts for the CPU and the high-end for most motherboard CPU sockets is 125W it's very unlikely you'd have an issue.