The first thing I suggest is read and learn a little bit about case airflow and cooling. It's only recently that people have started considering how important case airflow is... and it can be a time consuming job to get good cooling. I post this basic but by no means complete tutorial often. It's a work in progress:
There is much more to cooling than good cases and good CPU / GPU coolers. Modern GPU's make more heat than CPU... and getting that heat out of the case can be a challenge.
Setting up the case to cool properly is the hardest and most time consuming part of a build... And the most neglected by most builders.
We need at least as much volume of air flowing through the case as the total of CPU and GPU fans flow through their coolers. If we do not have as much air coming into and going out of case as CPU and GPU coolers are passing through and heating up than some of that heated cooler exhaust has to be re-circulated through the coolers. This means the cooler run hotter because the air going through them is hotter.
Cases, especially those with filters, usually benefit from fans with higher static pressure ratings than stock fans... "cooler" fans instead of "case" fans.
Intakes are typically more restricted than exhaust; air filter, more restrictive grill, HDD cage, etc.
I prefer more intake than exhaust. And don't confuse number of fans with amount of airflow... or airflow
is flowing cool air from intake to component and flowing hot air from component out of case without the hot air mixing with the cool air.
is lots of fans blowing air with some of hot air from components mixing with cool air making it warmer resulting in warm air not cooling components as well as the cool air will.
Putting fans in case as intake and/or exhaust is only the first step. These fans only move air in and out of case.
This does not mean heated air is not mixing with cool air.
Nor does it mean cool air is going to where it is needed.
Getting the air to flow inside of case properly is even more important. We still need to manage where the air flows inside the case. We can do this several ways; deflectors, cooler intake fans, exhaust fans, removing vent grills, using fans with higher pressure/airflow, building ducts to or from CPU/GPU cooler, etc.
Using a remote temperature sensor to monitor what air temps are is the key to finding out where the cool air is flowing and knowing heated air is not mixing into it. By monitoring this we can than make changes to get airflow the way we want it.
I monitor the temps with a cheap indoor/outdoor wired remote or terrarium digital thermometer. Twist a piece of stiff insulated wire into the last 8" of sensor lead so you can bend it to position sensor where you want it... like 40mm in front of your GPU cooler/radiator intake.. to see what the air temp going into CPU / GPU cooler is compared to room temp. The closer it is to room temp the better.. Shouldn't be more 5c maximum, 2-3c is what I usually end up with after 30 minutes full load on both CPU and GPU.
Warning: Spoiler! (Click to show)