if your planning 2 amp minimum, you may want to dip your toes into a multi-tap approach or switcher module following the atx on its own, as 2x 10.75V minimum is a big amount of heat being pissed away,
as your likely to only be using the regulator stage as an output, you cant make use of the 7V difference between 12V and 5V, as the 5V rail on just about every atx supply can only source and not sink current on the 5V rail, (just incase you try it from fan mods on forums)