why both the air direction is out
one side should be intake fans
and other side should be outtake fans
That's not a fan's, that's is GPUs. OP drawing a vertical GPUs positions.
What do you think??
It depends on GPUs airflow, what your GPUs are used? Many concepts of the cooling system, but it depends on a few factor. Ex, cards airflow, what kind of a rig you are used, rig dimensions etc.