Even if open it’s worth considering - unless you literally have exterior airflow source blowing in the side, pockets are pooling. To give you an idea, i have roughly the same setup - granted it just runs a slack lamp - but i don’t even need a cpu fan, just the stock heatsink and the case is closed. Intakes and exhaust, unless you got a watercool chiller airflow, airflow, airflow is paramount.
(My main beast has a 250mm window fan plus intakes/exhaust, ambient temp is about 8c over room temperature even when thrashing)