Hi coyi1895,
Your Corsair AX1200i will be fine on US 120V power as it's adaptive with power correction etc (100v - 240v). The only thing you may need is the power cord itself to plug into US outlets, if you don't already have one. They can be found at any PC supply store in the US or purchase online.
I recommend removing your graphics card from the motherboard, in case your pc gets bumped around during shipping. You can wrap it with a bath towel or two, and place it back within the case or box it separately. Or at least try to protect anything internal from possible damage from being bumped around or even dropped, as well as protecting the same way on the outside.
I wish you safe travels, and I'd like to be one of the first to Welcome You to the US.