2x140MM Vs 3x120MM – PC Cooling

It is important to have a decent fan setup when cooling your PC. A decent fan setup passively improves the cooling of all the components in the system.

Obviously, we all want a cool system, we don’t want our expensive parts overheating, that’s why many cases allow us to install fans. Installing case fans act as a passive cooling system, comprised of intake and exhaust fans.

Intake fans take air externally, typically cool air to cool the components within the system. And exhaust fans eject warm air, they’re usually placed on top of the PC as warm air rises.

More Intake Or Exhaust Fans For PC?

When installing fans on your PC case, you want more intake fans, although they’re equally as important. The reason you want more intake fans is to create positive pressure.

More intake also means more cool air circulating around in your PC, more cool air equals cooler components.

There are a few terms you need to understand when talking about airflow. CFM(Cubic Feet per Minute) = The amount of air moved by a fan.

What Is Positive Pressure & Do I Need It?

positive pressure

Positive pressure is when you have more intake airflow than exhaust, but is this all necessary? We all want a cool PC and there are many hazards that prevent us from achieving that.

Dust is minimized when you have a positive pressure config. The dust is only minimized in a positive pressured environment if all your intake fans have dust filters.

When you have a positive pressured environment, the air needs to find a way out. The air can escape through vents, gaps, and other exit points.

What About Negative Pressure?

Negative pressure does have its place too, exhausting more air than you’re intaking is what creates negative pressure. Negative pressured environments have lower temperatures but by only a small margin. The marginal difference simply isn’t worth it, at a cost for a few degrees you will have a dustier PC which will increase the temperatures over time.

If you have a negative pressure config, then your fans will create a vacuum, which will result in dust getting sucked in through gaps in your case. This is the only real downside to having a negative pressure environment, but it’s a big price to pay. If you have a dust-free environment, and you properly filter every opening, a negative environment can be advantageous.

How Many Case Fans Do I Need?

PCs will generate a ton of heat when running heavy loads. Also, taxing games graphically will stress the processor as well as the GPU which will generate a ton of heat. You may be tempted to fill in all your slots with fans. While this may work, it’s best to have a strategic approach to this.

More fans + Less RPM = Less Noise. Fewer fans + Higher RPM = More Noise. This is true if they’re moving the same amount of air. It’s up to you how you want your setup to be. Just remember, a positive pressure environment has more intake and less outtake. And a negative pressured environment has more outtake, than intake.

A decent setup would be 2*Front(Intake) + 1*Rear(Exhaust) + 1*Top(Exhaust). This is a total of 4 fans since there are two intakes and two exhaust, having the intake at a higher RPM would ensure for a positive pressure environment. If you’re on a budget, you can get away with 2fans, one intake, and one exhaust.

What Fans Should I Install?

case fan

120MM Vs 140MM Case Fans

When going for case fans, the default is a 120MM fan. 140MM fans are quieter and they do move more air, but 120MM is still the standard for PC case fans. Depending on your case, your 120MM slots may accept 140MM fans it’s worth a try, but generally speaking, you will be installing 120MM fans.

Speaking about raw performance, 140MM will outperform 120MM fans in every aspect. 140MM fans are able to move more air at lower RPMs compared to 120MM fans. If your 120MM slot can take 140MM fans, then I recommend going for the 140MM fans, as they’re quieter and they move more air.

Which Are Better: 3x120MM Or 2x140MM Case Fans?

If you’re stuck picking between 2x140MM fans and 3x120MM fans, I can help you make a decision.

3x120MM fans will push more air through the system, but only by a small margin. 3x120MM fans will cost you more money, it is also louder, and it will draw more power.

2x140MM fans will push marginally less air through the system, it will cost less, it will also be quieter, and you will be drawing less power.

For raw performance, 3x120MM is the best option, for efficiency, 2x140MM fans are the best option. It all comes down to what your personal preference really.

High Static Pressure Vs High CFM

There are really two types of fans you should know about, High static pressure, and High airflow. For case fans, high static pressure isn’t really desired, you should almost always go for high airflow. Static pressure is only necessary when you need to force air inside small openings such as heatsinks and radiators.

If you have a lot of obstructions inside your case, then a high static pressure fan may be advantageous. For example, some cases are blocked off by hard drive cages that inhibit airflow, here is where you could install high static pressure fans.

High airflow is rated by their CFM(Cubic Feet per Minute) basically, the amount of air a fan can move. In open environments, this is advantageous. You don’t want to go over the top with the CFM as high CFM fans can get extremely loud. If you got the tolerance for noise then go ahead.

You should go for a balance of airflow and noise, you can find that between 50-80CFM.