How to cool my computer?
I have 4 fans, 1 bottom (the power supply fan) 1 top, 1 front and 1 rear, i made the bottom, top and front as intake and the rear as exhaust, but it seems my computer gets hot eventually. I do not have side panel slots for other fans.
Reverse top one to exhaust, you need as much flow as possible, just blowing air around inside the case will not cool anything. Also make sure that nothing like cables etc. doesn't interfere with air flow and it evenly covers whole MB and parts.
Fan's and ventilation are not omnipotent, you also have to take care of elements like CPU and GPU if they are hotter than what they should be.
While it is true that "warm air rises to the top" in confined spaces with very little air flow, that is NOT what happens in a computer case with four fans pushing air around! The important factor to consider is to maximize air flow, and that usually is done best by balancing intake and outflow, and by arranging a clear flow path. Many people arrange air flow from front (intake) to back (exhaust), and / or bottom (intake) to top (exhaust).
OP, how are you controlling the fans? I expect the one in the PSU is not adjustable, so you have 3 that you can control. Are they connected to mobo headers using automatic control, or have you done something else that might limit their performance? I hope you are not using "Low-Noise adapters".