honestly hate to burst your bubble, but in short, no... you really need about 50 (actual, not equivalent) watts of Fluorescent per plant for "exceptional" bud growth, maybe even more than that. and being in an old computer case you're limited with how much light you can put it, but the plants are going to get way too big. just think of it this way, when the plant goes from veg. stage to flowering stage it on average triples in size, so even if it's 6 inches, it's gonna get to be about a foot and half which will probably hit the lights and it's gonna want to branch out in all directions which it wont be able to, if you really tried you could probably get 1 plant to grow and bud in there if it is extremely short, but for the time and effort you'd be better off buying an eighth. and fluorescent light diminishes really fast, so you want the light as close without touching the plants as possible... good luck man, and READ READ READ, thousands of peeps on here have tried just about everything method of madness to doing it, so never hesitate to search for an issue, or read up on other peoples threads, cause chances are if you have a question, it's been asked before! goodluck again!