Currently, I have 2 120mm front fans and the 200mm side fan as intake. I have a Corsair H100i with the fans at the top as exhaust and also the rear 120mm fan as exhaust. I believe this is the most suggested fan setup everywhere I have seen and it's doing me good so far.
There is space at the bottom for another 140/120mm fan.
My questions are:
1) If I get another fan for the bottom, should I use it as intake or exhaust? In addition to your suggestion, please tell me if it will interfere with the airflow or will actually prove to be good for cooling.
2) Should I get a 140mm or 120mm fan for this purpose?
3) Is it really necessary to add a bottom fan or should I just leave it as it is?
More about :corsair carbide 500r bottom fan question
1 intake, putting more cold air in should improve cooling not that you need to.
2 does not matter
3 I would leave it as is since you will be sucking dust from the floor with that fan, and it looks like you have plenty airflow already!
Ah, that's what I was thinking too but you confirmed it. Overall, I don't think there will be any difference in the temperatures at all. Maybe the idle temperature will be lowered by 1 ° - 2 ° but it doesn't seem necessary.
Also, I have been researching quite a bit and don't really agree that it doesn't make a difference if you have a 120mm or 140mm fan. A bigger fan will push/pull more amount of air and that too at a less RPM - which means better cooling and lower noise.