I wouldnt bother with a PC case. Why cramp your conditions...

Couldnt you find a storage box maybe 1m high x 60cm x 60cm. That sound more like a grow box to me.

Remember that the plants will need a fan inside to train them. You could even add a small carbon filter to it too in time.

In this space you could have 4 healthy dwarf low riders in 1sq foot each. You could make a bank of 1 foot florescent tubes. As many as you can fit.

I made one of them for my veg room. I looped a cable to each one. For veg you would need the 6300k daylight/bright white tubes. For bloom the 2700k warm white.

Wait a second and Ill take a photo of the light I made... Be sure you know how to do this though... It could be dangerous if you don't terminate the cables correctly.

Attachment 283902 Attachment 283903

Here are a few photos of my set up. Im adding these photos to let you know what a grow tent should include.

Here you see my LED light hanging from an adjustable chain and 4 x 20w CFL hanging over the sides of the LED light. The CFL are there for heating purposes as the LED light runs cool.
On the left is my 'training' fan. This is necessary to make the stems strong on the plants. It comes on for 15 minutes every 2 hours. The 4 inch flexible tubing is my fresh air intake.

Attachment 283904 This photo came in upside down... I dont know why....

This next photo is the top of the tent. on the right side is the centrifugal, speed controlled extractor fan. This is a proper extractor and it stays on 24/7 on the lowest speed. Attached to the extractor is the Can9000 carbon filter. I can have all the weed I want in this tent and you would not smell it at all even if you stood right beside the tent. this is important as I live in an apartment complex. Oh, and my tent is 120 x 90 x 90. It is in my bedroom right beside my wardrobe. You can also see all the timers used to control all the various appliances in the tent. Always remember to keep electrics above your waist and water below the waist. This minimises the risk of fire etc.

Attachment 283905 This photo is upside down too ! Sorry

And here are some photos of my babies

Attachment 283906

So anyway, as you can see, growing good weed takes more than a PC case. There are lots of other factors to take into account. I learned all of these the hard way. Eventually you come to realise that to do it right you need to gleam as much as you can from your peers and research. Before I started this grow I did an enormous amount of research and I saved money to get a proper grow tent with all the necessary equipment. A chain is only as strong as its weakest link. This rings true for growing weed. Problems can arise if you make a mistake in a number of areas; lighting, heat and burning, bleaching plants, excessive stretching due to poor lighting, humidity, mould due to poor air circulation, soil mix, nutrient burn, pot size and pot binding, drainage and root rot... the list goes on.

I hope it all woks out well for you. My only advice for you is to learn as much as you can from other peoples grows. The link to my grow journal is in my signature.

Take care

S.L.