What are the pros and cons of positive vs negative pressure in PC cases?

1 Positive pressure

Positive pressure means that you have more intake fans than exhaust fans, or that your intake fans are more powerful than your exhaust fans. This creates a higher pressure inside your case than outside, and pushes some of the air out through the gaps and vents. The main advantage of positive pressure is that it reduces dust buildup inside your case, since most of the dust is filtered by the intake fans or blown out by the excess air. The main disadvantage of positive pressure is that it can increase the temperature inside your case, since the hot air from your components may not be expelled efficiently.

2 Negative pressure

Negative pressure means that you have more exhaust fans than intake fans, or that your exhaust fans are more powerful than your intake fans. This creates a lower pressure inside your case than outside, and pulls some of the air in through the gaps and vents. The main advantage of negative pressure is that it can lower the temperature inside your case, since the hot air from your components is quickly removed by the exhaust fans. The main disadvantage of negative pressure is that it can increase dust buildup inside your case, since most of the dust is sucked in by the negative pressure and may not be filtered by the intake fans.

3 Balanced pressure

Balanced pressure means that you have an equal number and power of intake and exhaust fans, or that you adjust the fan speed to achieve a neutral pressure inside your case. This creates a balanced airflow that neither pushes nor pulls air through the gaps and vents. The main advantage of balanced pressure is that it can provide a good compromise between temperature and dust control, since the air is circulated evenly and efficiently. The main disadvantage of balanced pressure is that it may require more fine-tuning and testing to find the optimal fan configuration and speed for your case.

4 How to measure pressure

One way to measure the pressure inside your case is to use a digital manometer, which is a device that measures the difference in air pressure between two points. You can attach one end of the manometer to a fan or a vent inside your case, and leave the other end outside. The reading on the manometer will tell you whether you have positive, negative, or balanced pressure. Another way to measure the pressure inside your case is to use a simple tissue paper test. You can hold a piece of tissue paper near a gap or a vent in your case, and observe whether it moves towards or away from the case. If it moves towards the case, you have negative pressure. If it moves away from the case, you have positive pressure. If it does not move, you have balanced pressure.

5 How to adjust pressure

One way to adjust the pressure inside your case is to change the number or size of your intake and exhaust fans. Generally, adding more intake fans or using larger intake fans will increase positive pressure, while adding more exhaust fans or using larger exhaust fans will increase negative pressure. You can also adjust the pressure inside your case by changing the fan speed or direction. Generally, increasing the fan speed or reversing the fan direction will increase the pressure difference between intake and exhaust fans. You can use software tools or hardware controllers to adjust the fan speed or direction.