I have a lot of excess CPU fans to incorporate into the system , and I agree that pulling the heat off of the boards will keep the lights optimal, but the problem is removing heat from the grow area too. I can't use CO2 because I turn over the air too often in order to keep the temp down, and the benefit does not outweigh the cost. The summer months put a strain on my system; I wish I could outdoor. The LED's are the best option, Maybe put the COB's up top, and standard LED's on the sides, with ample airflow to rid heat waste. Naija, I think that you can build a nice system for a few $1000 to make it nice. Get a few standard full spectrum lights; 1K Watts or more, and a few COB's, and you will get sweet yields. Play with the growth, and build from there. You might even consider a HPS to round out your bloom.