I just bought Thermaltake V21 case for a budget gaming build. The case is going to hold AMD FX6300 CPU, GTX 750 Ti video card, 8GB of RAM and one SSD. All powered by 550W power supply. Nothing else in the case. Could somebody recommend how many fans should I add besides the 200mm front one that's included with the case? I am going to use stock CPU cooler as I am not going to overclock it.