Go to a local hardware store and buy yourself a small plug in power meter such as (http://www.amazon.com/Energy-Meter-LCD-Display-EM100/dp/B000RKVK52). This will allow you to measure your pc's power consumption.
If your input is running less than 80 % of your psu's rated output then you have some room to play. Keep in mind 430 watts is the rated output so if you keep you input under that number then by the time inefficiencies are accounted for you will likely only be loading your psu to 375 to 400 watts max output.