Well, I have just started a project to recycle a pair of cases with 250 watts, and I just bolted one on top of the other. Given the basic electronics involved the two should work very well. So, all the talk about needing 300 watts seems to be making you impulsive. You could wait till the prices drop and grab another 250 watt case at or atx. I'm still thinking through this project, so far I've assembled the parts(blue tinted acrilic for the casecover). Invention is the father of the mother.