[Josh Hambright]

I dont believe that there is any 'minimum' amount of space persay, just keep in mind that you do want their to be sufficent air flow going to and from the victors, i am assuming your refering to the muffin fans on the victors. I have cut it close in the past, probably around 1/2" but i dont know if i would recommend it again, with that sort of clearance you run into other problems other then just air flow, like the amount of effort/time it takes to access things and change out parts, tighten connections, change connections, running wires, these sort of things are also things you want to consider when determining the amount of clearance around components.

But to answer your question more directly... as long as there is sufficent air flow, and the components wont over heat, i'd say 1/2" is fine, but not ideal.