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Computer Fans: Information and Recommendations

PC Fans

Fans are becoming more and more necessary for modern computers. They’re used to simply move air through the computer or cool specific components. What more people should realize is that not all fans are the same, and it is a wise choice to select high quality fans that last long, fit your noise tolerance and provide enough airflow for your needs. In this thread I’ll make recommendations on fans to choose from, but first lets go over some terms you should know.

 

Terms and Abbreviations

RPM – Revolutions per minute. Measure of the complete rotations completed by the motor hub/fan blades. The higher the RPM, the more air movement but noise also increases. A more powerful motor is needed to achieve high RPM reliably, therefore motor noise might also increase.

CFM – Cubic feet per minute. Measure of the speed of air movement. Higher means more airflow, but increased RPM leads to increased CFM, therefore higher CFM fans will also be more noisy. The design and amount of fan blades affects CFM as well.

DBA – Decibels. Measure of noise. Higher is louder. Here is a useful sound chart.

Static Pressure – Measured air pressure. Commonly overlooked. Higher static pressure means the fan can output air that can more easily overcome the resistance to airflow. High pressure fans are especially ideal for fans installed on heat sinks or radiators, since the air will be forced through the fins and heat pipes more easily.

Undervolting – Reducing voltage to the fan via a fan controller to lower fan speed. Fans that undervolt well emit a normal fan noise, while fans that don’t undervolt well make odd sounds and pitches.

Fan Sizes

Computer fans come in a variety of sizes. The most used sizes include 40mm, 60mm, 80mm, 92mm and 120mm. 140mm fans are becoming more common as well, and some companies offer even larger fans such as 180mm, 200mm, 220mm, 230mm or 250mm. The thickness of most 60mm-140mm fans is 25mm, but some exceptions include the extra high pressure 38mm thick fans and there are some other rare exceptions. The larger fans tend to be slightly more thick.

Smaller fans have to spin faster in order to create more airflow, while larger fans can spin at a lower speed and still provide adequate airflow and much less noise. Over time you will have your own preferred fan sizes.

 

Connectors

Fans have cables and connectors on them since they need to get power from somewhere. 3-pin and 4-pin fan connectors are most common, and 2-pin connectors can be found as well. Then of course there are regular molex connectors. There are adapters for these sizes so compatibility is not an issue. Many fans also support Pulse Width Modulation (PWM) technology. Information on this can be found here.

  • Four Wires – If you encounter a fan with four wires, then you’re probably looking at a PWM fan. Two special wires are present – one for RPM sensing (usually blue) and one for PWM fan control (usually yellow).
  • Three Wires – Most fans include three wires. The last wire is for RPM sensing. The RPM sensor wire will be yellow or blue. This applies for PWM fans as well.
  • Two Wires – No RPM sensing or control, a two wire fan is running at full speed.
  • Molex Connector – Plugs into your power supply, thus the fan will be running at full speed.

Power supplies have many peripheral connectors which can be used for one or more fans. Occupying the fan headers on a motherboard is recommended, since this allows you to control the speed of the fans in the BIOS, for 3-pin and 4-pin PWM fans. You can also get a fan controller, which allows you to plug your fans into multiple channels allowing you to control fans separately. Some computer cases include built-in fan controllers.

Bearings

The bearings of a fan is also important. These affect motion between the moving parts inside of the fan. Here is an overview of commonly used bearings in computer fans. The following information has been taken from wikipedia, and I added my own modifications and information.

  • Sleeve Bearings – Features two surfaces lubricated with oil or grease as a friction contact. Sleeve bearings are less durable as the contact surfaces can become rough and/or the lubricant dry up, eventually leading to failure. Sleeve bearings may be more likely to fail at higher temperatures, and may perform poorly when mounted in any orientation other than vertical. The lifespan of a sleeve bearing fan may be around 40,000 hours at 40 °C. Fans that use sleeve bearings are generally cheaper than fans that use ball bearings, and are quieter at lower speeds early in their life, but can grow considerably noisier as they age.
  • Rifle Bearings – Similar to sleeve bearings, but are quieter and have almost as much lifespan as ball bearings. The bearing has a spiral groove in it that pumps fluid from a reservoir. This allows them to be safely mounted horizontally (unlike sleeve bearings), since the fluid being pumped lubricates the top of the shaft. The pumping also ensures sufficient lubricant on the shaft, reducing noise, and increasing lifespan.
  • Ball Bearings – Though generally more expensive, ball bearing fans do not suffer the same orientation limitations as sleeve bearing fans, are more durable especially at higher temperatures, and quieter than sleeve bearing fans at higher rotation speeds. The lifespan of a ball bearing fan may be around 63,000 hours at 40 °C. Some fans use one ball bearing, some use two and some use one ball and one sleeve. The latter is cheaper and less effective.
  • Fluid Bearings – These have the advantages of near-silent operation and higher life expectancy than even ball bearing fans, due to the lack of contact with the shaft, bearing and thrust plate. However, these fans tend to be the most expensive.
  • Magnetic Fluid Bearings – The fan is repelled from the bearing by magnetism. Stabilizes the rotor axis. Noctua’s Self-Stabilizing Oil Pressure Bearing (SSO and SSO2 Bearing) is one of the most popular magnetic fluid bearings.

 

Blade Design

Many computer fans have a different fan blade design so I’ll list the more noticeable ones. Different blade designs are not just done for aesthetic reasons or to be unique – the design of the fan blades can severely affect CFM, static pressure and even noise level to some extent.

You will see only a few things vary with different blade designs. The number of blades as well as the curve/direction of the blades. You will also see a difference in space between each blade. Adding more fan blades can result in more air movement, but if they’re too close together you’ll end up with less air movement. Thicker/wider blades are good at directing air straight forward, for better static pressure. This is also the reason most fan blades are curved.

Triple Blade Design – Used on nearly every house fan or non computer fan, but some computer fans use it too such as Delta EEB fans and their 120mm x 76mm fan. To be honest, I couldn’t tell you why this design is ever used. The three blades are usually curved a lot so that they can actually move a decent amount of air in a more straight path. But these three blades obviously have to revolve faster to be as effective as a fan with more blades, so these are more noisy and have limited performance. Skip fans with this blade design.

Delta EFB fan with a triple blade design.

Wide Blade Design – Many computer fans have seven blades but are widespread so that there is less of a gap in between them. You can see this design used on most Sanyo Denki and Panaflo fans. This design allows for greater static pressure and doesn’t limit airflow much so it’s a great design.

San Ace H1011 with its wide blade design.

Wavy Blade Design – Every now and then you’ll come across a computer fan with wavy blades. Cooler Master’s BladeMaster fans use this design, and so do Enermax fans. This design forces air in a straight pattern, improving static pressure, and due to the gap between the blades a good amount of air is being moved as well. Overall it is a good design.

Cooler Master XtraFlo 120 Red LED fan with wavy blades.

Directional Fan Blades – Some fans have integrated grills attached to the back of them, behind the fan blades. The most effective ones are known as directional fan blades – these are counter-spun to the fan blades, directing the air straight forward. Delta and Nidec were probably the first manufacturers to offer computer fans with this design. Silverstone has a slightly altered design on their Air Penetrator fans.

Most fans with this design have more directional fan blades than fan blades, but this can limit airflow. Delta introduced the PFB series which offer 11 fan blades and 9 directional fan blades. These happen to be their best fans, offering the highest static pressure and CFM. Airflow is less restricted since there are more fan blades than directional fan blades, and the added fan blades improved static pressure compared to their older fans.

Silverstone’s Air Penetrator fans have seven fan blades and a very dense integrated grill which is counter-spun to the fan blades. As a result, there is an improvement in air direction. Air is moved more straight than other fans. But the grill is awfully restricted so CFM takes a big hit. This isn’t as much of an issue on the AP181, AP182, and AP141 due to their larger size and RPM. But the AP121 suffers from this, judging by its 36 CFM rating. Most people are better off skipping the AP121, but the AP141 and AP182 are very useful fans.

Silverstone AP182 – seven fan blades with a counter-spun grill.
Delta PFB series fan. Eleven fan blades that are pretty much straight. The nine directional fan blades improve the direction of the airflow.
Silverstone’s AP121 demonstration.

 

Fan Placement

Putting fans in random spots in your computer is not going to help. You want fans to intake air from somewhere, preferably outside of the case and from other fans that intake air from outside of the case. You also want fans that exhaust air out of the case. For more information on preferred airflow methods, please have a look at my Airflow Guide.

I will go over different types of air pressures encountered in computers, although my airflow guide also goes over them.

Negative Air Pressure – Negative air pressure is probably the most common. It should really be avoided. In order to have negative air pressure, you must have more exhaust power than intake power. As a result, air is passively drawn in through open slots and ventilation. This would bring in more dust, and make it harder for video cards to exhaust air since the flow of air is going against it.

Positive Air Pressure – Positive air pressure is not as common in computer cases, but it is a preferred method of cooling. In a positive air pressure system, you must have more intake power than exhaust power. As a result, air passively leaves the case through open slots and ventilation. This reduces the amount of dust in the case, and it makes it easier for video cards to exhaust air since the flow of air is going with it.

Neutral Air Pressure – Neutral air pressure means you have equal intake power and exhaust power. In a neutral air pressure system, there is less air passively moving into and out of the case. This causes a lack of air movement in some areas of the case, sometimes causing hot spots, or places where heat builds up.

 

Brand Names

Some brand names offer a large selection of high quality fans, earning them a recommendation and a spot on the following list.

  • Be Quiet! – Quiet, as the name suggests, but not great for radiators. Excellent PWM functionality despite 3-pin connectors.
  • Delta – Best choice for ridiculously awesome cooling with no noise tolerance, although not all their fans are extremely high RPM (the only reason why many are loud, downvolt them and they’ll be quieter than most due to their quality). High grade server fans using either single or dual ball bearings. Endless amount of fan options, in all sizes.
  • EK – Their Vardar fans are great for radiators and are fairly quiet.
  • Nidec – They manufacture (Scythe) GentleTyphoons and other great fans that can be found on some power supplies (Antec Signature series). They manufacture very high end server grade fans using either single or dual ball bearings. Endless amount of fan options.
  • Noctua – Some of the absolute best fans for most gamers and enthusiasts, using the best fan bearings on the market (SSO and especially SSO2, both are magnetic fluid bearings). Wide variety of fan options.
  • Panaflo – Panasonic. Great mix of airflow, pressure, reliability, and relatively low noise. They mostly (or maybe even exclusively) use very good fluid bearings.
  • Phanteks – Good case fans, and their high pressure fans are good but not the best nor best value for their purpose.
  • Protechnic – They have at least some reliable, effective fluid bearing fans. Server grade.
  • Sanyo Denki – Known for great undervolting and low noise compared to most others. Very high end, server grade, but they have some lower noise options too. They usually use dual ball bearings. Available in all shapes and sizes.
  • Scythe – GentleTyphoon series are their best but their S-Flex series are very good. Beware, they have many low quality fans too. Should probably avoid all others from them.
  • Sunon – Reliable server grade fans. Mostly sold by industrial suppliers, thus bare wire in most cases. Single or dual ball bearing, very wide variety of fans.
  • Thermalright – Look for their FDB series which are the same as the Scythe S-Flex (both of which use the Sony fluid dynamic bearing), as well as their TY series fans which are some of the absolute best (not for radiators/heatsinks though).
  • Xigmatek – Good budget fans, not on par with any of the above.
  • Yate Loon – Good budget fans, not on par with anything above Xigmatek.

Of course there are exceptions, but the above brand names are some of the best either in quality or price to performance, some of those rock both of those worlds.

 

Suggested Retailers

You’re most likely going to order your fans online, but visiting your local Fry’s or Microcenter is a good idea. The following websites have a nice selection of fans (among other products) and don’t scam you.

Of course there are other good sites to choose from, but these are the more common sites. For server fan inquiries, continue reading for recommended sites. Also keep an eye on places like massdrop.

 

How To Acquire Delta, Nidec, Panaflo, Sanyo Denki, and other Server Fans

Delta, Nidec and Sanyo Denki are some of the very best fan manufacturers and the best choices for extremely powerful cooling. You can find some of their fans at the websites listed above, but for high prices and it’s still a limited selection. So how do you go about acquiring these fans? You will have to buy them from industrial suppliers instead. They sell a wide variety of Delta, Nidec and Sanyo Denki fans for lower prices than you’d expect. They’re the best choices for bulk orders. The downsides? No connectors are typically present. Just the sheathed wires so you’ll have to add the connectors yourself.

  • OnlineComponents – Excellent supplier for Delta fans.
  • MPJA – Variety of rare fans, best site I’ve found for Nidec fans.
  • Newark – They have tons of Sanyo Denki fans. To simplify and shorten your search, click here for a list of 120mm x 25mm fans, here are their 120mm x 38mm fans, here are their 140mm fans and you can find other, odd sized Sanyo Denki fans such as 150mm and 172mm.

So there you have it. If you have a case with those large 200+mm fans, you’re better off swapping them out for multiple 120mm fans or even 140mm fans. Doing this will not only provide better airflow, but also remain just as silent if you choose your fans wisely, and improve lifespan since there are no high quality 200+mm fans. Silverstone 180mm fans are pretty good – particularly the FM-181 which is the only one with ball bearings. But their AP181 fan is even better despite using sleeve bearings. The sleeve bearings are modified so that they don’t perform badly in a horizontal position. Their air penetrator fans have a grill on them to direct air. This impedes air movement drastically but improves direction. Here is a review on the AP181 fans.

 

Why You Should Avoid Scythe Slipstreams and Scythe Ultra Kazes

These fans are popular due to their low price and high CFM rating. But they’re cheap for a reason. SlipStreams are just terrible fans. Why? Here is a list.

  • Sleeve Bearings – You can see the downsides to these at the top of the post.
  • Poor Static Pressure – Making it a poor choice for heat sinks and radiators. Yate Loon 120mm high speeds do a much better job at cooling, as you’ll see in the links below. And Yate Loons cost even less.
  • Cheap Build Quality – The motor is designed for 80mm fans. This contributes to a short lifespan. The motor will crap out before the sleeve bearings will.
  • Horrible Undervolting – When undervolted, they’ll make loud clicking noises and/or whining which is just annoying, and they don’t stay within RPM specification.

The Ultra Kazes have the same issues, minus the significant build quality issues which aren’t as bad on the Ultra Kazes. But they still undervolt terribly, have sleeve bearings and poor pressure of only about 3 mmH2O. The Noctua NF-F12 Industrial 2000 has way more static pressure (about 4 mmH2O) at less than 30 DBA, with much more reliability.

Here are some links you should look at, even after looking at this guide.

“The Well Dressed Megahalems – A test of 65 fans and 112 fan setups on a Prolimatech Megahalems heat sink.

Jab Tech Yates vs Petras Yates

Fan Testing

XtremeSystems Fan Review

The Anatomy of the Silent Fan

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