You cannot make it today without quality power supply unit. Many users underestimate relevance of this component and do not consider it as important as the processor or graphics cards.
Nowadays, computer cases can be small or big. Thin or thick. Long or short. The choice is yours. Pick quality processed cases for reasonable price.
The computer fan provides airflow in the computer cabinet. The resulting airflow sucks cool air into the cabinet and blows warm air out of the cabinet.