I currently have 2 120mm case fans. One fan in the front that pulls air in and another at the back that blows pulls air out. I want to buy 2 more 120mm fans and install them on the side of the case.
My questions is which way should the fans be facing? Should I put the 2 new ones on the side pulling in air and leave the other 2 as they are? Should I take the one in the back and reverse it and then have the 2 new ones pulling air out instead?
If you have more intakes you'll have a positive air pressure, that means that the case intakes more air than exhausts. So you can leave it those 2 fans in the side and the front as intake, and the back one as exhaust.
You'll improve cooling and force the dust to stay out of your case (Your intake fans must have a dust filter for this to work)
If you have more exhausts dust will get into the case and the cooling is not going to be enough.