Thursday, 31 October 2013

Choosing case fans - it's not as simple as you think.

Case fans. They're the basis for system cooling, as they keep a flow of fresh, cool air flowing through your system. However, choosing a case fan is not as simple as buying the most expensive one on the basis that it'll be the best, but evaluating three different statistics:

-Noise. Often found measured in dB-A. This is a measure of the attenuated noise that emits from the fan itself. Those looking for a quiet system should try and keep this as low as possibe, but less noise usually means less airflow and static pressure.

-Airflow. Often found measured in Cubic Feet per Minute (CFM). This is a measure of the amount of air that a fan can pass at a given speed in one minute. The higher the CFM measure, the more airflow there is in your case, as a generalization. We'll go into this further later on.

-Static Pressure. Often found measured in millimeters of water (mm-H2O). Static Pressure is effectively a measure of how forcefully a fan can drive it's airflow, hence why high static pressure fans are good for radiators and heatsinks, as the airflow is easily impeded. 

Part 1: Intake Fans
Intake fans are basically any fans that will be used to push air into the case. These are generally found at the front, side and bottom of many cases. In order to push air into the case, they must pull air through the front. This is usually through a mesh or vents (depending on your case). 

For example, a BitFenix Shinobi case uses two mesh strips along the front of the case to draw air in through. This is difficult due to the low surface are that air can be drawn in through, therefore more static pressure is needed.

Meanwhile, a case like the Antec 300 uses a large front mesh to draw air in through. This is easier due to the much larger surface area that air can be drawn in through, meaning static pressure is not as important.

So, for intake fans we should be looking for HIGH airflow and MEDIUM static pressure. A few recommended fans can be found below:
-Akasa Apache Black Series (Quiet at full speed but with audible clicking)
-BitFenix Spectre Pro Series (Quiet yet audible at full speed)
-Corsair SP Series (1450rpm version is quiet, 2350rpm version is loud)
-Yate Loon D12SL Series (Quiet at low speeds - some stores sell fake Yate Loons)
-Zaward Golf III Series (Innovative blade design means silence at low speeds)

These recommendations are made from professional reviews and personal experience of some of these fans. Most, if not all of the above recommendations, are available in both 120mm and 140mm formats.

Part 2: Exhaust Fans
Exhaust fans are any fans that are used to pull warm air out of the case. Generally found at the top and rear of many cases, they are often unrestricted and therefore Static Pressure is not as important as airflow here. 

Generally, exhaust fan mounts are only grilles, rather than having dust filters and such things that would impede the flow of air. Therefore, in most cases you want exhaust fans to have HIGH airflow. More recommended fans below:
-Aerocool Shark Series (Quiet at full speed, silent with 7v reduction cable)
-Corsair AF Series (1450rpm version is quiet, 2350rpm version is loud)
-Noiseblocker Blacksilent Series (As the name suggests - very quiet fans)
-NZXT FZ Series (High airflow with acceptable noise levels)

Once again these recommendations come from professional reviews and personal experience. Again, most of the above fans are available in both 120mm and 140mm formats. 

Part 3: Heatsink and Radiator Fans
When it comes to selecting fans for heatsinks and radiators, you're getting involved in a whole different scenario. This is because there are a number of variables. Seeing as you're reading this far, you probably know about radiator fin density (how many fins there are per inch). Higher fin density means more static pressure is needed, and lower fin density means high static pressure becomes less important - the same is the case with conventional heatsinks.

So, to generalize, you're looking for fans with HIGH static pressure and HIGH airflow. Once again, you can find a list of recommended fans below:
-Corsair SP Series (1450rpm version is quiet, 2350rpm version is loud)
-Noctua F12 Series ('Unique' colour scheme - brilliant fans nonetheless.)
-Scythe Gentle Typhoon Series (The Ultimate Radiator Fan - enough said!)
-Yate Loon D12SL Series (£5 for a fan with great static pressure - once again, enough said!

So, I hope I have at least done something to spread a little light on the shady area of PC fans. One thing to always remember is don't trust the manufacturer. If their claimed specifications were always correct, the Coolermaster R4 would be the best fan in the world. 

If you do have any questions, don't hesitate to leave a comment!


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