I have the cheapest case ever. it's not even worth mentioning.
I knew from the start I had to mod the cooling, or the thing would overheat.
I recently added a filter to my custom 120mm side mounted and sucked all the dust off my HSF and wiped off some other components. but now I had reduced airflow.
so, I sit and look at my case, and realize the stock exaust fan (not PSU) was actually forcing the cooler air out of my case, and it is located directly under the PSU, so flipping it would just bring in hot air from the PSU
so instead I go grab some wall mounting squares (about 1" x 1" and cut them into small squares and remount my fans around my case for desired circulation effect.
I took the one that was under the PSU exaust and made it blow air up from under the graphics card.
then I have a 90mm antec mounted underneath my PS blowing air right over the CPU fan, all aimed at my blowhole and PSU fans.
temps are down on the CPU (where I wanted the circulation to take effect) but up a degree on the chipset.