Some computers briefly spin their fans at startup as part of a hardware check. That can be normal. But if the fan stays at full speed, the computer may be reacting to heat, a missing sensor reading, dust blockage, firmware settings or a failing fan.

Notice whether the fan slows down after a minute, whether the computer boots normally, and whether performance feels reduced. A loud fan with slow performance can point to thermal throttling.

Recent service or damage matters

If the fan issue began after cleaning, repair, a drop or liquid exposure, internal connectors and sensors should be considered. A heatsink that is not seated properly can make temperatures rise quickly.

For desktops, check whether the loud fan is the CPU cooler, graphics card, case fan or power supply. Each path is different.

Do not block the vents

Using a laptop on bedding, carpet or a soft couch can block airflow. Desktops pushed tightly against walls can also struggle to exhaust heat.

AEPC / AKL East PC diagnoses fan noise and overheating issues in Auckland. Send a short video of the sound if it helps describe the problem.