1. A method of updating baseboard management controller firmware for fan speed control comprising: providing a baseboard management control system that includes: a storage device for storing therein a firmware associated with operation of a fan unit of a computer device, the firmware containing fan parameter data that is associated with control of a rotary speed of the fan unit; a temporary storage device that is used to store the firmware received from the storage device, and that has a first temporary storage region, and a second temporary storage region for storing therein the fan parameter data; and a baseboard management controller coupled to the fan unit, the storage device and the temporary storage device, the baseboard management controller controlling the rotary speed of the fan unit by executing the firmware stored in the temporary storage device; starting to receive, by the baseboard management controller in response to receipt of an instruction indicating a firmware update operation, fan parameter update data associated with control of the rotary speed of the fan unit, and storing the fan parameter update data thus received in the first temporary storage region of the temporary storage device; determining, by the baseboard management controller after completion of receipt and storage of the fan parameter update data in the first temporary storage region of the temporary storage device, whether or not the fan parameter update data stored in the first temporary storage region of the temporary storage device is valid; and updating, by the baseboard management controller after determining that the fan parameter update data stored in the first temporary storage region of the temporary storage device is valid, the fan parameter data stored in the second temporary storage region using the fan parameter update data stored in the first temporary storage region.