Remember... Wattage = Voltage X Amperage
So... 3.3v X 12A = 39.6 Watts
Edit: 5.0v X 25A = 125 Watts
(My bad, it was very early in the morning when I posted that, sorry.

)
That adds up to 165 Watts... That's about right.
I wouldn't believe what you read on the side of a cheap PSU anyway. The best way to find out is to plug it in and see what happens. But, I'd beg, borrow or steal a better PSU first...