Nice setup by the way Solidnickel.
Thats a good few amps/ and watts you are pulling when the three 480`s are at load.
I guess it comes down to the amp draw of each 480/ and the watt it pulls.
Then to check each 12v rail of the psu, and its amp output.
combine all three 480`s amp draw and then see if the four combined 12v rails of the Psu are higher.
Will tell you if it can cope with your monster setup.