2 questions about cooling

[Stuttgart 911]

1. If I have 5 fans, each running at about 21dB, how many decibels would that amount to? Is it possible to figure this out? I was wondering how loud all of these fans whould be together...

2. What would be good airflow for a mid-tower to keep it cool? Not including the HSF and PSU, I will have 81CFM going out and 80CFM going in. Is that good?

[Alaron]

The combined sound level of 5 21dBa fans is 27.989 dba ~ 28Dba. If you want to compute this type of thing in the future, use the equation:

Total= 10 x Log (10^(dba1/10) + 10^(dba2/10) )

So for your calculation, its 10^2.1 x 5 and take the log of that and then multiply by 10.

:)

For proper airflow, as long as you have cool air pulling in from the front and hot air exhausting in the rear of the case you shouldn't have temperature issues. Especially with 5 fans, you'll be fine. :)

[Panama Red]

Think you need to consider the amount of air volume in the case when calculating a desired amount of airflow. Ideally, you're trying to replace the heated air inside with cooler outside air faster than the air will heat up on the inside. Plus, the direction of flow is important. Too many fans can cause turbulence in the case which prevents air flowing out quickly enough and may create "hot spots" inside the case. Case design has a huge bearing on air flow too. A small frontal air inlet will prevent adequate intake of cooler air regardless of the fan you place behind that inlet. Antec's Sonata case is a good example of a restricted front inlet area. Another consideration to cooling (but less so) is the type of material the case is made of. Aluminum cases will dissipate heat more quickly than a steel one while plastic will work as an insulator and tend to hold the heat in. Just some random thoughts.

[Stuttgart 911]

My intake on the front is kind of small and it fits a 120mm. SHould I have that, the top and side fans as intake and the rear 2 exhaust? I also have 2 fans on my PSU.

[Spartan]

With 5 fans it won't be perfectly balanced and I would say have more exhaust than intake. If you have a 120 up front for intake then make the side an intake also and you should be fine. The top I would make an exhaust and the back an exhaust. That is somewhat similar to what I have on one of my machines and it works well.

-Spartan

[Panama Red]

Personally, I would make any rear fan exhaust and any front fan intake. A top mounted fan should compliment the air flow thru the power supply and it too should be exhaust. I'd place it over the CPU and in front of the power supply. The side fan should be an intake an be positioned to blow directly at the Graphics card or an area covering the graphics card and the cpu. By the way, nice selection of parts there Stuttgart 911.

[Stuttgart 911]

Heh, $54 on fans... I still have to buy that heatsink. I have Cricket to thank for the recommendation of the Stealths.