Hey, I have this same case with i5 2500k, MSI Z77 G45 motherboard and EVGA GTX 680 with an Antec 900 watt power supply.
I have 2 120 mm fans up front, 2 140 mm fans up top, 1 120 mm on the back and 1 140 mm fan on the side as an exhaust. I've been thinking of adding a 120 mm fan on the bottom as an intake. I would recommend that. I removed my hard drive cage so i have more room.