lets pretend sakto ang buga sa PSU fan nmo paubos(dili mo bleed ang exhaust inside sa casing), unya elevated na imo psu. the reason ngano init sya is because wala ka intake fans that is able to lower the overall case temperature.
remove that side fan na naa sa tunga, it will only disrupt the air flow. air should be flowing in one direction, with exhaust suppose to be at the top(hot air rises, cold air sinks, dba?)