If you have a fairly restrictive grille or pattern of holes, this will cause you not to feel the airflow through the rad. This is possibly why Corsair recommend fitting it as an intake. It is easier to pull air through the grille than push air through it. As you have 2 x 140 on top as exhaust, it may be better to configure the H80i as in intake.
There is probably little actual difference in cooling effect doing this but it may be worth a try.
Spacing the H80i fan from the case may also be effective, allowing the air to flow better through the rad and using the 2 x 140 to pull the hot air from the case.
How good is the H80i cooling with the FX8320?
