Cheers for the info so far
On modthebox.com it says that the cm stacker comes with a by-pass dual PSU connector, anyone know what that is?
If I use another power supply it's going to be a 330 watt antec true power, combined with a 550 watt true power I will have 880 watts of power, More than enough power for the system.
here is the link to the review http://modthebox.com/review334_3.shtml
EDIT: that power supply calculating site said I would need 406 watts minimum with one card, it said cards were 110 watts each so that gives a 516 watt power supply minimum, 880 watts is gonna be fine!