UPDATE: No I don't need an exhaust fan
As the title says, do I even need an exhaust fan in a decent positive pressure system, as long as metal grills are cut?
Currently working on a Corsair 650D (case pics)
for a new positive pressure build (overclocked Sandy Bridge i5-2500K). Measuring and cutting two-layer 12mm sound-dampening foam for the entire case, and will also remove all the metal grills by intakes and exhausts. All intakes will use DEMCiflex dust filters
, which are rated for 15% CFM loss. Top intake will also sport a wire grill for extra protection, but other than that nothing but the dust filters.
The picture below is not my setup, it just gives you an idea of the case.
In my setup I will be using the following fans:
The layout I am considering is this:
By using that barrier to section the bottom of the case off, the entire airflow from the front intake should be better directed at the GPUs and CPU. The AX850 PSU runs its own little airloop anyway. The GPUs are unknown still, so I don't know how much warm air they will be putting back into the case, or if they push it out back.
My original plan was to put a temperature controlled Noctua NF-P14 FLX
(140mm PWM, 750~1200 RPM, 42.5~66 CFM, 10.1~19.6 dBA) as rear exhaust fan, but with all the CFM coming in, and the TY-150 on the CPU cooler, I am thinking perhaps it isn't necessary, and might even be detrimental because it can't keep up with the airflow. I know the rated CFM numbers from companies aren't always accurate, but assuming they are to compare intake and exhaust, I'll be getting over 100 CFM into the case, taking the dust filters into account as well, and the Noctua will struggle with that at low RPMs.
The CPU cooler (Thermalright Archon) is doing just fine
with a single fan in push, also at low RPM (those results are with the TY-140), rivaling even the Silver Arrow that uses 2 fans, so the Noctua as exhaust won't do much good there either: