New
#11
Au contraire!
On the line side of your electrical supply (the wall plug) that is 20A at 115 volts AC (US residential standard).
Your 1200 watt power supply is DC voltage. It probably only draws 10 Amps at 120v AC to run at full rated power.
You go with a 20A outlet because you will probably be plugging more than just the PC into it.