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Lesson 10- Cooling computer building component

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In lesson 10 we'll cover cooling of the computer case, types of cooling fans, cables, what features and specs to look for when shopping, and how much you can expect to pay.

When selecting the cooling fans for your computer you need to consider the size, speed, the amount of air they move, the noise the fans make and how they will get their power.

Fan Size and Speed
Most computer cases have space for size 80mm and or 120mm fans. Most cases will come with fans already installed with options to add extra fans. Check the case specs to be sure.

The the size of the fan and the speed the fan blades rotate, determines the amount of air moved.

The amount of air moved is measured in cubic feet per minute or CFM.

Noise Level
The speed of the fan, it's build quality and it's size determines how much noise it makes.

The noise level of a fan is measured in decibels or dB.

When buying a 80mm fan, look for one that can move at least 30 CFM of air with less than 30 dB of noise.

When buying a 120mm fan, look for one that can move at least 60 CFM of air with less than 30 dB of noise.

This will ensure good airflow in the case, with little more than a whisper level of noise.  For an almost quiet fan, look for 20 dB.

Speed Controls

Fans with adjustable speed controls are also an option.  These fans let you tailor the fans speed and noise level to your liking.

If you want more control over all of the cooling fans you can connect them to a fan controller. The controller sits in a 5.25 inch bay next to your DVD drive or a 3.5 inch where a floppy drive would go.  This allows you full control of each fan. Some models give you temperature readings from inside the case.

Power Connectors
Case fans can connect to either a standard 4 pin molex connection from the power supply or a 3 pin connection on the motherboard.  If you're going to use a fan controller, keep in mind that most will only support fans with the 3 pin power connectors.

Many case fans have both the 4 pin molex and smaller 3 pin connections.

Connecting through the motherboard is best since the fan not only gets power from the connection, but the motherboard can also monitor and control the fans speed and sound a warning if the fan ever stops spinning.

Most motherboards have at least 2 of these 3 pin fan connections. Check the specs or take a look at the motherboard you buy to be sure.

Case Fan Locations
All computer cases have a place for at least 1 fan at the front of the case to bring in cool air.

A good case will either come with or have at least 1 place to add another fan next to the CPU and video card to move the hot air out.  Some cases will have spots for bottom, side and top fans as well.

When you’re shopping for fans

  • Look for 120mm fans that move at least 60 CFM of air and makes less than 30 dB of noise.
  • Look for 80mm fans that move at least 30 CFM of air and make less than 30 dB of noise.
  • Be sure the fan has a 3 pin connector, so it can be monitored by the motherboard or plugged into a fan controller.
  • Expect to pay between $5 and $15 per fan.

In the installation lessons we will install the case fans into the system and create clear airflow inside the case.
Fan Warranties


Computer building cooling fans are generally very reliable and will last for many years. That said, it's best to buy cooling fans with at least a 3 year warranty.

This level of warranty is standard for most manufacturers, but not all. So be sure to check the warranty coverage before buying cooling fans.


Fan Reviews

To find more reviews do a search in your favorite search engine (Google, Yahoo) for the model number of the fan you're interested in.

Buying Cooling Fans


Whether you buy a 120mm, 80mm fan or another size fan, there is no shortage of choices for computer building. Below are several sites that will help you find the lowest price from a reputable merchant.


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