Having some airflow problems

[FugSnug]

Hello People , I'm having some problems with my GPU which gets to about 80 degrees (MSI GTX 1080 Gaming X) but if i pull off the side panel the temps drop drastically i mean like 65 ish(My CPU temps drop by 5 degrees too) . So what i'm thinking is that it has to do with airflow, and im thinking to put 2 140mm fans at the top, I currently have 2 120mm fans intake and 1 120mm fan exhaust. Can you give me any tips wether i should install those fans at the top?

 

[Computers Taste Like Metal]

Practice good cable management, try to have equal pressure (same amount of exhaust as intake), make sure no dust in case, make sure case is in open area with good ventilation, and if none work get bigger case.