I'll be 100 % honest and say, if you can skip the pc case, its just the wrong shape.
try and make something that while still very small "micro" and fits a proper led light. like the smallest models from mars hydro. the footprint of these lights is only like 60 cm by 60 cm.
with the progression in led lighting you can now yield up to or more than 1 gram per watt of led light. the base models from mars hydro is around 100 watts
the best place to see micro grows is the site ic mag.
hope this small amount of information can help anyone thinking of starting a micro grow