The bearing type of a DC computer case fan is another critical factor that affects its performance, lifespan, and noise level. Sleeve bearings are one of the most basic and commonly used bearing types. Sleeve bearings consist of a shaft that rotates within a sleeve filled with lubricant. This design is relatively simple and cost - effective. Sleeve - bearing fans are often used in budget - friendly computer case fans. They can operate quietly under normal conditions, but over time, the lubricant in the sleeve can evaporate or become contaminated. When this happens, the friction between the shaft and the sleeve increases, leading to louder operation and eventually reduced fan lifespan. Sleeve - bearing fans are also more sensitive to the orientation of the fan. If the fan is not installed in the correct position, the lubricant may not be evenly distributed, further accelerating wear and tear.

Ball bearings, on the other hand, offer better performance and durability. Ball bearings use small metal balls to reduce friction between the rotating shaft and the stationary housing. This design allows for smoother rotation and can handle higher loads compared to sleeve bearings. Ball - bearing fans have a longer lifespan as the wear on the components is significantly reduced. They are also less affected by the fan's orientation, making them more suitable for various installation scenarios. However, ball - bearing fans tend to be noisier than sleeve - bearing fans at high speeds due to the mechanical contact between the balls and the races. Hybrid bearings combine the advantages of sleeve and ball bearings. They typically use a sleeve - like structure for the main support and a small ball - bearing mechanism for additional stability. Hybrid - bearing fans can offer a balance between cost, noise level, and lifespan, making them a popular choice for mid - range computer case fans.