Fan Controller Buying Guide

Introduction

In the course of compiling reviews for this site, it occurred to me that that while the list of specifications for a fan controller are potentially quite long, the same handful of features tend to be emphasized on manufacturers’ websites and by customers in their reviews on sites such as Amazon and Newegg. These features tend to be ones that can easily dictate whether the controller matches the requirements of the buyer. There is no point in buying a dual-bay controller, for example, if our hypothetical buyer does not have two drive bays to spare. There are a few other features that, while not as conspicuously featured in ad copy or reviews, may have an impact on the functioning of the controller or on the overall look and feel of the product and therefore are also worth mentioning. With this in mind, it is possible to compile a fan controller buying guide based on these criteria.

Fan Controller Buying Guide - Lamptron FC-2

The Lamptron FC-2 is a good example of a manual fan controller.

Manual or automatic fan control

Put simply, does the controller merely allow the user to control the speed of the fan or fans (by controlling the voltage of the fan), or does it allow the user to intelligently control fan speed based on the temperature inside the computer? If the user only wants to throttle the fan speed back sometimes, then a manual controller will likely be sufficient. In some cases, a very simple controller, or even just a rheostat spliced into the fan wire might do.

In other instances, the user may want to vary the fan speed based on the temperature. An automatic fan controller typically works by reading the temperature from a thermal probe inside the computer. If the temperature remains below a user-set threshold, the fan will run at reduced speed. If the temperature exceeds the threshold, the fan will run at full speed. In some cases, the control is more granular, and the user can set the speed at which the fan runs both below and above the temperature threshold. Automatic fan controllers include thermal sensors, which need to be placed by the user wherever the temperature needs to be read. This means an extra set of wires inside the case, which makes things a bit more complicated. Still, automatic control is a more efficient way of running the fans.

Fan Controller Buying Guide - Xigmatek CSF-CBK33-U01

The Xigmatek CSF-CBK33-U01 is but one example of a one-channel fan controller.

Number of channels 

Generally, you want to have as many channels as you have fans to control. If you have more fans than your controller has channels, you can always connect more than one fan to a single channel by means of a Y-connector. If you are using an automatic fan controller, however, keep in mind that in this case, more than one fan will be sending RPM readings back to the controller. Since it is unlikely the controller has the circuitry to deal with this, the RPM readings will likely be erratic. The best way of dealing with this is to leave the wire for the fan whose RPM reading you want the controller to see intact, and cut the yellow wire for all other fans, thus ensuring that only one fan sends RPM readings to the controller.

Except for very simple controllers such as the Xigmatek CSF-CBK33-U01 (a one-channel controller), most controllers have at least four channels. The Lamptron FC8 has eight controllers, which should be enough for most users. Installing a second fan controller is also an option, although this will increase your power requirements, so be sure your PSU (power supply unit) can handle it.

Wattage

Fans have different power requirements, but most fans require 12 volts DC to run at full speed. This means we can calculate the necessary wattage via Joule’s Law (P = V * I). if the fan draws 0.3 amps, then the fan requires 12V * 0.3a or 3.6 watts to run. Most controllers seem to provide at least 5 watts per channel, which is a little low, but should be enough for most users. Some controllers, such as the Lamptron FC-2, boast as much as 50 watts per channel. One thing to consider is that most fans draw a little bit more when the fan starts, so you probably want to leave a little headroom. For example, if the controller outputs 10 watts per channel, you probably want to make sure the fans on each channel do not require more than about 8.5 watts per channel during normal usage.

The one obvious corollary of this which nonetheless deserves mention is that as the controller’s output wattage increases, they are going to draw more power from the PSU, so you will want to make sure your PSU is rated high enough. The recommended minimum PSU output for the Lamptron FC8, for example, is 600 watts.

Fan Controller Buying Guide - Aerocool Touch-2100

Some fan controllers require two drive bays, like the Aerocool Touch-2100.

Number of drive bays required

Most fan controllers require a single 5.25″ drive bay for installation. A number of them require two 5.25″ drive bays. If you do not have a 5.25″ drive bay to spare, you still have a few options. A few controllers can be installed into a 3.5″ drive bay (the Scythe KM03, which has both 5.25″ and 3.5″ variants, comes to mind). And a few do not require a drive bay at all. The Sentry LXE is an external fan controller which has a separate LCD display and the controller itself is on a PCI card. On the other end of the price spectrum, the Xigmatek CSF-CBK33-U01 is a simple one-channel manual controller which can be mounted onto any available expansion slot. Most systems to which you would contemplate adding a fan controller, however, will probably have at least one available full-sized drive bay.

3 or 4-pin fan connectors

Most of the new fans have 3-pin mini connectors. The pulse width modulation (PWM) fans have 4 pins, and the ability of a fan controller to accommodate PWM fans, either by having 4 pins on the fan header on the controller, or by including 3-to-4 pin adapters with the controller, is always a plus. [Older fans usually had large 4-pin Molex connectors, but unless your fans are over 10 years old this should not be an issue.] If you have one or more PWM fans that are going to be controlled, you will want to find out if the controller you are buying supports it.

Ability to completely shut off fans

Controllers control the RPM speed of a fan by regulating the voltage. Most fans require 12 volts DC to run at full speed. The relationship of speed to voltage is linear, so as the voltage is cut, the fan speed is cut proportionately. But the fans require about 5 volts DC to run at all, so fan speed can only be cut back to 40 percent before it shuts down. Some controllers only allow the user to cut back fan speeds to about 40 percent. In some ways, this is a good fail-safe feature, since it means no matter what the user sets the controller to, the fans are always running. Still, the ability to shut off the fans completely is a nice added feature for those who put a premium on noise reduction.

 

Fan Controller Buying Guide - NZXT Sentry 2 alt view

The NZXT Sentry 2, one of many automatic fan controllers with a temperature alarm.

Presence of temperature alarms/fan alarms

It is always a good thing if the fan controller sounds an audible alarm when temperature thresholds are reached. Fortunately, many of the automatic fan controllers have such alarms. Unfortunately, many alarms only sound for a short period of time, so unless you are near the computer when the alarm sounds, you’re likely to miss it.

Some controllers have alarms that sound if a fan is unplugged or if a fan stops running, which is another good feature to have, since the failure of a fan will, if not addressed, lead to overheating and hardware failure.

Accuracy of readings

This seems pretty obvious: all other things being equal, you want the reported RPM speeds and reported temperatures to be accurate. The manufacturer-provided specs provide little guidance on this matter, and most likely you will have to plow through the product reviews to find out how accurate they are.

Colors

So far I have focused on the practical aspects of controllers, but in many cases they are installed in gaming rigs. Aesthetics will, in most cases, at least be a factor for these users, creating a demand for controllers with colorful backlights and displays. Manufacturers have accommodated this demand, and it is not uncommon to see products with bright LED backlights, as well as the ability to change the colors of the backlight. Some controllers with LCD screens have similar capabilities (for example, the Aerocool Touch-2100).

Ability to turn off the display (or backlight)

A bright display can be visually pleasing and generally is easier to read. But it also can create a fair amount of light pollution, so the ability to turn it off is always a plus.

Conclusion

These criteria are, in my opinion, the most important ones to consider when purchasing a fan controller. But your mileage may vary. I am approaching it from the perspective of a computer hardware enthusiast; others may rank these criteria differently or have entirely different criteria. I’d love to know your opinion, especially if you’re a hardcore gamer or like to make custom mods to your PC.

External Links

Here are links to some of the fan controller manufacturers mentioned in this article:

 

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