I recommend the Coolermaster HAF 932 because it has superior ventilation, airflow, and cooling. The ATCS 840 has a front panel that restricts airflow.
captvicenzo - Both cases are designed for a standard atx motherboard with 7 expansion slots on the rear panel. If you meant drive bays, one extra drive bay will not make any difference for the typical user or gamer. It is very rare for someone to need 11 drive bays.
i think as i am going to use my PC for 8 to 10 hours daily , the air flow should be optimized
so as per you will HAF 932 be a better choice than ATCS 840 ?