Manually speed-adjusting CPU fans offer users a more hands-on approach to controlling the cooling of their computer's CPU. These fans typically come with a control knob or a set of jumper pins on the fan or a connected control module. By adjusting the knob or changing the jumper settings, users can directly set the rotational speed of the fan.

One of the main advantages of manually speed-adjusting CPU fans is the flexibility they provide. Users who have a good understanding of their computer's cooling requirements and the specific characteristics of their CPU can fine-tune the fan speed according to their needs. For example, if a user knows that their CPU runs hot during a particular application but the default fan speed is not sufficient, they can increase the speed manually. On the other hand, if the computer is being used for less demanding tasks and the fan noise is a concern, the speed can be decreased.

However, this type of fan requires more user intervention compared to intelligent speed-adjusting fans. Users need to monitor the CPU temperature themselves and make appropriate adjustments. If the fan speed is set too low, the CPU may overheat, especially during heavy workloads. Conversely, if it's set too high, the fan will generate excessive noise and consume more power. Additionally, manually speed-adjusting fans may not have the advanced features like thermal protection or the ability to communicate with the motherboard that intelligent fans possess. But for those who enjoy having more control over their computer's components and are willing to put in the effort to manage the cooling, manually speed-adjusting CPU fans can be a viable option.