There really is a learning curve to this growing thing. One of the things you need to do in order to get a plant to harvest is to learn what your indoor conditions need to be. It is great to be able to put together something for $30, but only if it is going to meet the parameters that cannabis needs to grow.
Ideally, temps should be kept between about 65 and 80. You most likely need more light. You want a minimum of 3000 lumens range per sq ft in the 6500K for vegging and 5000 lumens per sq ft in the 2500K range for flowering. I don't think there is enough head space to put a HID in there, but you may want to look into 2' T5s. The T5s put out about 50% more light per watt than CFLs. In addition, the CFLs are taking up too much headroom. You want lights with the thinnest profile you can get.
Regardless of the size of the grow or the heat issues, you need to exchange the air in your space. You need a continual supply of fresh air for proper photosynthesis. This is best accomplished with exhaust fans. I am not sure if the PC fans can handle this.
Have you decided how you are going to keep them small enough to grow in something that is only 27" tall?