I'm going to upgrade my "gaming" PC. My case is a Ultra E-Torque and I don't know if I should buy 1 or 2 fans. Inside the case I have 2 HDD, a 7850, and a Core 2 quad. I would get a fan to exhaust air from the back, but do I need one to take air in. If I do I was thinking about a Corsair Air Series AF and a Corsair Air Series SP both 120mm. Is the Corsair SP fan really necessary because I'm on a tight budget with upgrading. Any help is nice have a good day.