Shouup, that won't help your PC. It'd probably make it hotter to tell the truth, because air is circulating rather than being blown out in a closed compartment like if it was closed.
My temps are with my PC with a 120mm one blowing in at the front, a Cpu fan, a hard drive fan, two PSU fans (one blowing in, one blowing out) a graphics card fan, and a 88mm fan blowing out at the back (there was two though one snapped
...Hasn't really made a difference though)
So thats 7 fans! Its only in games the CPU temp gets above 50 degrees