I believe there are 2 kinds of fans, the normal everyday fans and the turbine kind like you have on the cards.
The normal fans blow in every direction, but the turbines take it from one side and push it out to the other. The turbines take air from inside the case and blow it out towards where your monitors plug into.

I think in your setup you are blowing the hot air coming out back to the cards.

Put your hand where you would plug your monitor in, you will feel the hot air coming out. Or try it with a lit cigarette, and see where the smoke is being sucked in...