I've been looking into computer fans for ventilation and trying to apply them to my grow space. My gro space is 5 ft wide 2 ft deep and 5 ft tall. I have a 400w hps ready to mount. I've planned on using 1 120mm fan to exhaust air from the upper left side and 1 120mm fan for active intake from the bottom right side. I will also be using a fan (not a computer fan) to move the air between the light and plants. Is this feasible? Anyone know from experience how helpful cpu fans really are? How many cfms should I be looking for from the computer fans?