Originally Posted by MrHyde
This is absolutely correct; the "best" airflow is really only going to be determined for your system through trial and error. I'm using the rig below, and I tried every combination of fans as intake or exhaust before finding that the coolest temps were with both 120mm fans on top as intake, the 120mm in front as intake, the back fan as exhaust, and passive exhaust through the open grills on the side. Was a good 5 degrees cooler than any other setup.
Experiment with your rig; while we can theorize as to what's the best setup for you, only you know where all your cables run, and all the intricacies of your case and build. Fans are easy to move, don't be shy; experiment!
We want airflow
. We want cool air flowing in and heated air flowing out with none or as little as possible of the heated air mixing with cool air that is going to components to cool them... Because hot air does not cool components very well.
Lots of fans make lots of airblow
mixing the heated components exhaust with cool intake air and raising the temp of air going into components.. and this is not good airflow
. Good airflow is the intake vents/fans flowing cool air to components. We want components heated exhaust air to flow out of case without mixing with any of the other air in the case. Every degree hotter the inside of case is translates a degree hotter the air going into CPU & GPU.. and that translates into CPU & GPU being the same degree hotter. So if your case is is 10c hotter than your room and you get good airflow the case temp will be 2-3c hotter tha room.. than CPU & GPU will be 7-8c cooler than it was before.
23c room + 10c case = 33c and cooler 68c, CPU is 68c (CPU is 35c hotter than air into cooler)
23c room + 2c case = 25c than cooler is 60c, CPU is 60c (CPU is 35c hotter than air into cooler)
Hope that makes sense.
I monitor temperatures in case with a cheap (£4.00) indoor/outdoor or terrarium digital thermometer with wired remote sensor. Doing this allows me to see how case is performing relative to room temp. sensor can be positioned different places to make sure there are no hotspots.. like in front of CPU cooler intake or GPU intake. Using this you can configure fans so air flows through the case keeping cool intake air separated from hot exhaust air.