Hmmm....I just took a look at the Cooler Master case over at Newegg. According to their specifications the case only comes with one 120mm fan. There are options for adding several additional additional 120mm fans. I suggest adding one fan to the top of the rear panel to exhaust hot air from the case.
If you are going to be overclocking and using multiple graphic cards, then there will probably be additional heat to contend with. Take into considertation the case is a bit small for a mid-tower.
I also suggest reading a few technical reviews of the 430: