TW201419747A - Fna control system and fan control method - Google Patents

Abstract

A fan control system and a fan control method suited for a computer device are provided. The fan control system includes a fan, a board management unit, a power control module and a rotation-speed switching unit. The fan is driven by a control power and a rotation-speed control signal. When in a standby status of the computer device, the board management unit provides a fan enable signal, a rotation-speed switching signal and a first fan rotation-speed signal. The power control module receives a fan enable signal to determine whether to provide the control power or not. The power control module switches an auxiliary power or a main power to the control power according to a power-supply situation of the computer device. The rotation-speed switching unit switches the first rotation-speed signal or a second rotation-speed signal to the rotation-speed control signal according to the rotation-speed switching signal.

Description

Fan control system and fan control method

The present invention relates to a fan control technology for a computer device, and more particularly to a fan control system for automatically switching a fan speed and adjusting power supply in a standby state, and a fan control method thereof.

When the computer device is operating in a Standby state (ie, in the S5 state, soft off state defined in the Advanced Configuration and Power Interface (ACPI)), Although the user believes that the computer device has been turned off, the computer device does not completely stop operating. That is, some of the devices in the computer device will still operate in the standby state. Because these devices still have cooling requirements, some fans still need to operate in standby mode.

In the past, a fan that is driven by an auxiliary power supply (AUX power) is installed in a device that still needs to be operated in a standby state, and the base management controller controls the fans. Since these fans are driven by the reserve power source, if the board management controller sets the fan speed too high, the power supply amount of the standby power source is instantaneously insufficient to cause the power supply to be reset, and the computer device is unstable. Therefore, the substrate management controller may still make a mistake when automatically setting the fan speed in the standby state, and the above situation may occur.

On the other hand, since the fan is driven only by a single power source (pre-power source), when the computer device returns from the standby state to the normal operation (runtime) In the state of the state, the heat dissipation effect of the fan can be greatly reduced, which does not meet the heat dissipation requirements of the current computer device under normal operating conditions.

The invention provides a fan control system and a fan control method, which adjust the power supply and control speed of the fan according to the power management state of the computer device and the power supply condition thereof, so that some devices in the standby state can maintain a certain degree of heat dissipation. In addition, in order to avoid the failure of the substrate management unit, the embodiment of the present invention additionally provides a monitoring device to maintain the heat dissipation performance of the computer device.

The present invention provides a fan control system suitable for use in a computer device. The fan control system includes a fan, a baseboard management unit, a power control module, and a speed switching module. The fan is driven by the control power and the speed control signal. When the computer device is in the standby state, the substrate management unit provides a fan enable signal, a speed control signal, and a first fan speed signal. The power control module is coupled to the baseboard management unit and the fan, and receives the fan enable signal to determine to provide control power to the fan. Moreover, the power control module switches the preliminary power source or the main power source as the control power source according to the power supply condition of the computer device, thereby providing the fan. The speed switching module is coupled to the baseboard management unit and the fan, and receives and controls the first fan speed signal or a second fan speed signal as the speed control signal according to the speed control signal, thereby being provided to the fan.

In an embodiment of the present invention, the fan control system further includes: a monitoring module coupled to the substrate management unit, the power control module, and the speed switching module. The monitoring module detects the fan enable signal and acts as a fan After the signal is disabled for a predetermined period of time in the standby state of the computer device, the monitoring module provides a forced operation signal during a forced operation period. Thereby, the power control module receives the forced operation signal to provide control power to the fan, and the speed switching module receives the forced operation signal to provide the second fan speed signal as the speed control signal to the fan.

In another aspect, the present invention provides a fan control method suitable for use in a computer device including a fan. The fan control method includes the following steps. The fan enable signal, the speed control signal, and the first fan speed signal are provided when the computer device is in the standby state. The fan is enabled according to the fan enable signal to determine whether to provide a control power. When it is decided to provide the control power to the fan, the preliminary power source or the main power source is switched as the control power source according to the power supply condition of the computer device. The first fan speed signal or the second fan speed signal is switched according to the speed control signal as a speed control signal. And the fan is driven by the control power source and the speed control signal.

In an embodiment of the invention, the fan control method further includes the following steps. The fan enable signal is detected, and when the fan enable signal is detected to be disabled in the standby state of the computer device, the predetermined period is counted. After the scheduled period has been counted and the fan enable signal is still not enabled, a forced operation signal is provided during the forced operation period. A forced operation signal is provided to provide control power to the fan. The second fan speed signal is provided as a speed control signal to the fan according to the forced operation signal. And, after the forced operation period, continuously detecting the fan enable signal.

Based on the above, the fan control system and the method thereof according to the embodiment of the present invention automatically adjust the power supply and the speed control of the fan according to the power management state (for example, the normal operation state or the standby state) of the computer device and the power supply condition thereof, so that the standby state is Some of the devices are capable of maintaining a certain level of heat dissipation. These devices can also use the same fan to achieve sufficient heat dissipation under normal operating conditions. In addition to automatically adjusting the fan speed through the baseboard management unit (substrate management controller), the fan speed can also be adjusted through the built-in fixed speed signal. On the other hand, the embodiment of the present invention also avoids the failure of the substrate management unit and additionally provides a monitoring device, which will forcibly start and operate the fan when the fan is not activated for a long time in the standby state, thereby maintaining the computer device. Cooling performance.

The above described features and advantages of the present invention will be more apparent from the following description.

1 is a block diagram illustrating a fan control system 100 suitable for use with a computer device including a fan 110 in accordance with a first embodiment of the present invention. The fan control system 100 includes a fan 110, a substrate management unit, a power control module 130, and a speed switching module 140. In this embodiment, a substrate management controller (BMC) 120 is used as a substrate management unit. Some embodiments may also use a chip set in a computer device, a south bridge chip, or a related physical circuit for controlling a fan. The permutation, the embodiment of the invention is not limited thereto.

The fan 110 of the embodiment is installed on a part of the device that still needs to operate in the standby state of the computer device, for example, the substrate management control. The device 120, the network module, a complex programmable logic device (CPLD) 150, etc. supported by the standby power supply AP. Therefore, the number of the fans 110 in this embodiment is not limited to one, and some embodiments may also be implemented by multiple fans. The ground end of the fan 110 is coupled to the ground voltage GND, and the power end of the fan is coupled to the output end of the power switch 134 of the power control module 130 to receive the control power source CP. The rotational speed of the fan 110 is controlled and adjusted by the rotational speed control signal 148 provided by the rotational speed switching module 140. Therefore, the fan is driven by the control power source CP and the speed control signal 148. The rotation speed control signal 148 of the embodiment is exemplified by a Pulse Width Modulation (PWM) signal, and a Pulse Width Modulation (PWM) signal can control the motor rotation speed in the fan 110.

The substrate management controller 120 can determine, under various power management states (eg, a normal operating state (S0 state) or a standby state (S5 state)), through various pipes. In this embodiment, the substrate management controller 120 knows the power management status of the computer device through other devices (for example, a power supply sequence unit). When the computer device is in the standby state, the substrate management controller 120 provides the fan enable signal 122 and the speed control signal 124, and when the substrate management controller 120 automatically controls the fan 110, the first fan speed is also provided. Signal 126 to adjust the fan speed.

The power control module 130 is coupled to the substrate management controller 120 and the fan 110. The power control module 130 receives the fan enable signal 122 to determine whether to provide the control power supply CP, and decides which control power supply CP is provided to the fan. 110. In the embodiment, the power control module 130 includes a power control unit 132 and a power switch 134. The power control unit 132 can be implemented using a Complex Programmable Logic Device (CPLD) 150, while the power switch 134 can be implemented with an analog switch having a large voltage carrying capacity. The power control unit 132 receives the fan enable signal 122 and determines whether the fan enable signal 122 is enabled, thereby indicating whether the fan 110 is rotated/driven in the standby state of the computer device. In other words, when the fan enable signal 122 is enabled, it indicates that the baseboard management controller 120 will control the fan 110 to drive in the standby state of the computer device. Therefore, the power control unit 132 receives the power supply signal 136 provided by the power supply in the computer device, thereby determining the power supply condition of the computer device, and providing the main power enable signal 137 and the preliminary power enable signal 138 according to the power supply condition. The power switch 134 receives the main power source MP and the standby power source AP, and provides the control power source CP according to the main power enable signal 137 and the preliminary power enable signal 138.

For example, when the primary power enable signal 137 is enabled, it indicates that the power supply has a primary power source MP. Therefore, when the main power signal 137 is enabled, the power switch 134 turns on the main power source MP to the output of the power switch as the control power source CP. When the main power signal 137 is disabled and the standby power enable signal 138 is enabled, it indicates that the power supply does not provide the main power supply MP and only the preliminary power supply AP is provided, so the power switch 134 turns on the standby power supply AP to the output of the power switch. The end serves as the control power source CP. Thereby, the embodiment of the present invention can dynamically adjust the control power of the fan 110 according to the power supply condition of the computer device. In general, when the computer device is in the standby state, since the main power source MP is not provided, the power is The source switch 134 can only use the backup power source AP as the control power source CP, and in the normal operation state, the power switch 134 can utilize the main power source MP as the control power source CP.

In particular, in the standby state of the computer device, the embodiment of the present invention can select two speed control modes through the speed switching signal 124 provided by the substrate management controller 120. The first type of speed control mode is to automatically control the speed of the fan 110 by the first fan speed signal 126 of the baseboard management controller 120. The second speed control mode is to control the speed of the fan 110 by using the second fan speed signal 147 (that is, the pulse width modulation signal of the fixed clock) provided by the speed switching module 140 in the standby state. Therefore, when the substrate management controller 120 often sends an excessively high fan speed signal to cause the power supply to be frequently reset, the internal circuit design or the user can adjust the speed control signal 124 to make the fan 110 have a fixed speed. The drive can be operated, and the fan 110 can also provide partial heat dissipation.

In the embodiment, the speed switching module 140 includes a state switching unit 142, a fixed speed signal generating unit 146, and a speed switching unit 144. In this embodiment, the state switching unit 142, the fixed speed signal generating unit 146, and the speed switching unit 144 can all be implemented by using the complex programmable logic device 150, but other similar devices (for example, logic) should be utilized by the embodiment. The circuit and the field effect programmable logic array (FPGA) are implemented, and the implementation manner is not limited thereto. The state switching unit 142 receives the speed switching signal 124 and the normal operation to the standby signal S0_to_S5. When the normal operation to the standby signal S0_to_S5 is enabled, it indicates that the computer device has been normal. The operating state enters the standby state, so the state switching unit 142 provides the speed adjustment signal 143 according to the speed switching signal 124. The fixed speed signal generating unit 146 generates a pulse width modulation signal of the fixed clock as the second fan speed signal 147 according to the preset parameters provided in the circuit design. In the embodiment, the fixed rotational speed signal generating unit 146 may be a fixed clock pulse oscillator, but the embodiment of the present invention is not limited thereto. The speed switching unit 144 is coupled to the state switching unit 142 and the fixed turn signal generating unit 146, and receives the speed adjustment signal 143, thereby determining to switch the first fan speed signal 126 according to the speed adjustment signal 143 (for example, when the speed adjustment signal 143/ The state switching unit 142 is enabled or the second fan speed signal 147 (for example, when the speed adjustment signal 143 / state switching unit 142 is disabled) as the speed control signal 148.

In view of this, the fan control system 100 can automatically adjust the power supply and speed control of the fan 110 according to the power management state (for example, the normal operating state or the standby state) of the computer device and the power supply condition thereof, so that some devices in the standby state are allowed. To maintain a certain level of heat dissipation, these devices can also use the same fan 110 to achieve sufficient heat dissipation performance under normal operating conditions.

In the middle of implementing the above-described first embodiment, it is found that when the substrate management controller 120 is controlled to control the fan in the standby state, an error sometimes occurs, causing the computer device to reset or the substrate management controller 120 to be inoperable. Therefore, in order to allow the fan 110 to have its heat dissipation effect when the substrate management controller 120 fails, the second embodiment in accordance with the spirit of the present invention additionally provides a monitoring device as an auxiliary protection mechanism for driving the fan to When the fan is not started for a long time in the standby state, some devices (such as complex programmable logic devices) that are still running and have few faults are used to forcibly start and operate the fan, thereby automatically maintaining the heat dissipation of the computer device. efficacy.

2 is a block diagram illustrating a fan control system 200 suitable for use with a computer device including a fan 110 in accordance with a second embodiment of the present invention. This embodiment is similar to some of the components of the first embodiment described above. Therefore, please refer to the above embodiments for partial description, and details are not described herein. Compared with the first embodiment, the monitoring module 260 is coupled to the baseboard management controller 120, the power control module 130, and the speed switching module 144. The monitoring module 260 detects the fan enable signal 122. When the fan enable signal 122 is disabled in the standby state of the computer device, it indicates that the substrate management controller 120 has stopped the operation of the fan 110. However, if the fan enable signal 122 is maintained in the disabled state for a long time, the first possibility is that the substrate management controller 120 considers that the computer device is not overheated and stops the fan 110 from operating; another possibility is that The substrate management controller 120 is no longer operational, so the fan enable signal 122 is not enabled.

If it is the latter case, the monitoring module 260 continuously detects whether the fan enable signal 122 has reached a predetermined period in the disabled state, and the predetermined period may be determined by the application of the embodiment according to the actual situation. When the predetermined period has been reached, the monitoring module 260 facilitates the provision of the enabled forced operation signal 270 during a predetermined forced operation period. When the power control unit 132 of the power control module 130 receives the enable forced operation signal 270, the main power supply is provided according to the current power supply condition. The signal 137 and the preliminary power enable signal 138 allow the power switch 134 to provide a corresponding control power CP (typically the standby power AP in the standby state) to the fan 110.

In addition, when the speed switching unit 144 of the speed switching module 140 receives the enabled forced operation signal 270, since the substrate management controller 120 may not be able to provide the automatically adjusted first fan speed signal 126 due to inoperability, the The pulse width modulation signal (second fan speed signal 147) of the fixed clock generated by the complex programmable logic device 150 is provided as the speed control signal 148 and supplied to the fan 110, thereby forcibly operating the fan 110. After the predetermined forced operation period, the monitoring module 260 resets and resets its internal register, and continuously detects the fan enable signal 122 to ensure that the fan 110 is forced after every predetermined period of time. Operate to avoid overheating of the computer device in standby mode.

In addition, when the predetermined period is not reached and the monitoring module 260 detects that the fan enable signal 122 is changed from the disabled state to the enabled state, it indicates that the baseboard management controller 120 is still normal, and therefore the monitoring module 260 is heavy. Set and return to its internal register, and continuously detect the fan enable signal 122, In this embodiment, the monitoring module 260 includes an inspection unit 262 and a timing unit 264. The inspection unit 262 is coupled to the counting unit 264. The checking unit 262 and the counting unit 264 can be implemented by using a Complex Programmable Logic Device (CPLD) 150, but the embodiment of the present invention is not limited thereto. The checking unit 262 receives and detects the fan enable signal 122. When the fan enable signal 122 is disabled in the standby state of the computer device, the counting unit 264 is activated to assist in counting the predetermined period. When counting unit 264 After the predetermined period has been counted and the inspection unit 262 detects that the fan enable signal 262 is still not enabled, the checking unit 262 provides the forced operation signal 270 during the predetermined forced operation period, and after the forced operation period. The fan enable signal 270 is continuously detected. In addition, if the detecting unit 262 detects that the fan enable signal 122 is switched from disabled to enabled during the predetermined period, it indicates that the baseboard management controller 120 still automatically adjusts the fan 110, so the checking unit 262 is heavy. The internal buffer of the checking unit 262 and the counting unit 264 are set, and the fan enable signal 122 is re-detected. The remaining actuation processes and structures of this embodiment are disclosed in the above related description, and are not described herein.

The above embodiment will be explained from another point of view. Fig. 3 is a flow chart showing a fan control method according to the above embodiment of the present invention, which is applied to a computer device. The steps S310 to S350 of FIG. 3 may correspond to FIG. 1 and the first embodiment of the present invention, and all the steps of FIG. 3 may correspond to FIG. 2 and the second embodiment of the present invention. Referring to FIG. 2 and FIG. 3, in step S310, the substrate management controller 120 determines the power management state of the computer device.

When the power management state of the computer device is in the standby state, the process proceeds from step S310 to step S320, and the substrate management unit (the substrate management controller 120) provides the fan enable signal 122, the speed switching signal 124, and the first fan speed signal 126. In step S330, both the power control module 130 and the monitoring module 260 detect whether the fan enable signal 122 is enabled. The power control module 130 determines whether to provide the control power CP to the fan 110 according to the fan enable signal 122, and the monitoring module 260 detects the fan enable signal. 122, to determine whether to proceed to step S360. The steps associated with the power control module 130 are described below.

When the fan enable signal 122 is enabled, it indicates that the substrate management unit has decided to provide the control power CP to the fan 110. Therefore, the process proceeds to step S335, and the power control module 130 switches the standby power source AP or the main power source MP according to the power supply condition of the computer device. , as a control power supply CP. At this time, since the computer device is in the standby state, the power control module 130 will switch the standby power source AP as the control power source CP.

On the other hand, if the power management state of the computer device is in the normal operation state in step S310, the process proceeds to step S315, and the power control module 130 switches the main power source MP as a control according to the power supply condition (normal power supply) of the computer device. Power supply CP.

In step S340, the speed switching module 140 detects whether the speed switching signal 124 is enabled. When the speed switching signal 124 is enabled, the process proceeds to step S342. The speed switching module 140 thereby switches the first fan speed signal 126 as the speed control signal 148 to enable the baseboard management unit to automatically control the fan 110. On the other hand, when the speed switching signal 124 is disabled, the process proceeds to step S344, and the speed switching module 140 switches the second fan speed signal 147 as the speed control signal 148 to operate the fan 110 at a fixed speed. Thereby, in step S350, the fan 110 can be driven by the control power source CP and the rotation speed control signal 148.

Go back to step S330 and the monitoring module 260. If the monitoring module 260 detects that the fan enable signal 122 is disabled, then step S330 proceeds to step S360, and the monitoring module 260 uses the counting unit 264 to count a predetermined time. And the checking unit 262 continues to detect the fan enable signal 122. In step S362, the checking unit 262 detects whether the fan enable signal 122 is switched from disabled to enabled during the predetermined period. If the checking unit 262 detects that the fan enable signal 122 is switched from disabled to enabled during the predetermined period, then the process proceeds from step S362 to step S335 (ie, when the step S362 is NO), and the monitoring is performed. The register in the module 260 is reset to zero to continuously detect the fan enable signal 122.

Going back to step S362, if the counting unit 264 has finished counting in the predetermined period, and the checking unit 262 detects that the fan enabling signal 122 has not been converted from disabled to enabled (that is, when the step S362 is YES), Then, proceeding to step S364, the checking unit 262 checks whether the number of times of monitoring reaches a predetermined number of times. If the number of times of monitoring does not reach the predetermined number of times, it indicates that the baseboard management controller 120 may still have not lost the operation, so the checking unit 262 returns from step S364 to step S360 to accumulate the number of times of monitoring.

If the number of times of monitoring does not reach the predetermined number of times, the process proceeds from step S364 to step S370, and the checking unit 262 provides the forced operation signal 270 to the power control module 130 and the speed switching module 140 during the preset forced operation period. Therefore, in step S372, the power control module 130 will provide the control power CP to the fan 110 according to the forced operation signal 270. On the other hand, the speed switching module 140 can provide the second fan speed signal 147 as the speed control signal 148 to the fan 110 while the power control module 130 is actuated or in accordance with the set sequence.

In step S380, the checking unit 262 determines whether a predetermined forced operation period has elapsed. When the forced operation period has not been reached (ie, When the step S380 is "NO", the checking unit 262 continues to perform steps S370 to S372. If the forced operation period has been reached (ie, when YES at step S380), the checking unit 262 returns to step S330 to continuously detect the fan enable signal 122.

In summary, the fan control system and the method thereof according to the embodiments of the present invention automatically adjust the power supply and the speed control of the fan according to the power management state (for example, the normal operation state or the standby state) of the computer device and the power supply condition thereof. Some devices in standby mode can maintain a certain degree of heat dissipation. These devices can also use the same fan to obtain sufficient heat dissipation performance under normal operating conditions. In addition to automatically adjusting the fan speed through the baseboard management unit (substrate management controller), the fan speed can also be adjusted through the built-in fixed speed signal. On the other hand, the embodiment of the present invention also avoids the failure of the substrate management unit and additionally provides a monitoring device, which will forcibly start and operate the fan when the fan is not activated for a long time in the standby state, thereby maintaining the computer device. Cooling performance.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100, 200‧‧‧Fan control system

110‧‧‧fan

120‧‧‧Baseboard management controller

122‧‧‧Fan enabling signal

124‧‧‧Speed control signal

126‧‧‧First fan speed signal

130‧‧‧Power Control Module

132‧‧‧Power Control Unit

134‧‧‧Power switch

136‧‧‧Power supply signal

137‧‧‧Main power enable signal

138‧‧‧Prepared power enable signal

140‧‧‧Speed switching module

142‧‧‧State switching unit

143‧‧‧Speed adjustment signal

144‧‧‧Speed switching unit

146‧‧‧Fixed speed signal generating unit

147‧‧‧Second fan speed signal

148‧‧‧Speed control signal

260‧‧‧Monitoring module

262‧‧‧Check unit

264‧‧‧counting unit

270‧‧‧Forcible operation signal

AP‧‧‧Prepared power supply

CP‧‧‧Control power supply

GND‧‧‧ Grounding voltage

MP‧‧‧ main power supply

S0_to_S5‧‧‧ Normal operation to standby signal

S310~S380‧‧‧Steps

1 is a block diagram showing a fan control system 100 in accordance with a first embodiment of the present invention.

2 is a block diagram showing a fan control system 200 in accordance with a second embodiment of the present invention.

3 is a flow chart illustrating a fan control method in accordance with the above-described embodiments of the present invention.

200‧‧‧Fan control system

110‧‧‧fan

120‧‧‧Baseboard management controller

122‧‧‧Fan enabling signal

124‧‧‧Speed control signal

126‧‧‧First fan speed signal

130‧‧‧Power Control Module

132‧‧‧Power Control Unit

134‧‧‧Power switch

136‧‧‧Power supply signal

137‧‧‧Main power enable signal

138‧‧‧Prepared power enable signal

140‧‧‧Speed switching module

142‧‧‧State switching unit

143‧‧‧Speed adjustment signal

144‧‧‧Speed switching unit

146‧‧‧Fixed speed signal generating unit

147‧‧‧Second fan speed signal

148‧‧‧Speed control signal

260‧‧‧Monitoring module

262‧‧‧Check unit

264‧‧‧counting unit

270‧‧‧Forcible operation signal

AP‧‧‧Prepared power supply

CP‧‧‧Control power supply

GND‧‧‧ Grounding voltage

MP‧‧‧ main power supply

S0_to_S5‧‧‧ Normal operation to standby signal

Claims (10)

A fan control system is applicable to a computer device, the fan control system includes: a fan driven by a control power source and a speed control signal; and a substrate management unit provided when the computer device is in a standby state a fan enable signal, a speed switching signal and a first fan speed signal; a power control module coupled to the baseboard management unit and the fan, receiving the fan enable signal to determine to provide the control power to the fan, And switching to a standby power source or a main power source as the control power source according to the power supply condition of the computer device, thereby providing the fan to the fan; and a speed switching module coupled to the substrate management unit and the fan, receiving and switching according to the speed The signal is switched to the first fan speed signal or a second fan speed signal as the speed control signal for providing to the fan. The fan control system of claim 1, wherein the power control module comprises: a power control unit that receives and determines whether the fan enable signal is enabled, and when the fan enable signal is enabled, Receiving a power enable signal to provide a primary power enable signal and a preliminary power enable signal according to the power supply condition of the computer device; and a power switch coupled to the power control unit, wherein the power switch receives a primary power source and Preparing a power source and providing the control power source, when the main power signal is enabled, using the main power source as the control power source; When the main power signal is disabled and the preliminary power enable signal is enabled, the standby power source is used as the control power source. The fan control system of claim 1, wherein the speed switching module comprises: a state switching unit that receives the speed switching signal and a normal operation to the standby signal, when the normal operation to the standby signal is enabled Providing a speed adjustment signal according to the speed switching signal; a fixed speed signal generating unit generating a pulse width modulation signal of the fixed clock as the second fan speed signal; and a speed switching unit coupled to the state switching unit And the fixed transfer signal generating unit receives and switches the first fan speed signal or the second fan speed signal as the speed control signal according to the speed adjustment signal. The fan control system of claim 1, further comprising: a monitoring module coupled to the substrate management unit, the power control module, and the speed switching module, wherein the monitoring module detects the fan a signal, and when the fan enable signal is disabled for a predetermined period of time in the standby state of the computer device, the monitoring module provides a forced operation signal during a forced operation period, wherein the power control module receives The forced operation signal provides the control power to the fan, and the speed switching module receives the forced operation signal to provide the second fan speed signal as the speed control signal to the fan. The fan control system of claim 4, wherein the monitoring module comprises: an inspection unit; and a counting unit coupled to the inspection unit, wherein the inspection unit receives and detects the fan enable signal When the fan enable signal is disabled in the standby state of the computer device, the counting unit is activated to count the predetermined period, and after the predetermined period has been counted, the fan enable signal is still not enabled. Thereafter, the inspection unit provides the forced operation signal during the forced operation period, and continuously detects the fan enable signal after the forced operation period. The fan control system of claim 5, wherein the inspection unit resets the inspection unit and the counting unit when the fan enabling signal is enabled during the predetermined period. A fan control method is applicable to a computer device including a fan. The fan control method includes: providing a fan enable signal, a speed switching signal, and a first fan speed signal when the computer device is in a standby state; Determining whether to provide a control power to the fan according to the fan enable signal; when deciding to provide the control power to the fan, switching a preliminary power source or a main power source as the control power source according to the power supply condition of the computer device; The speed switching signal switches the first fan speed signal or a second fan speed signal as the speed control signal; The fan is driven by the control power source and the speed control signal. The fan control method of claim 7, wherein switching the preliminary power source or the main power source as the control power source according to the power supply condition of the computer device comprises the following steps: determining whether the fan enable signal is enabled, and When the fan enable signal is enabled, a power enable signal is received to provide a primary power enable signal and a preliminary power enable signal according to the power supply condition of the computer device; when the primary power signal is enabled, the primary power source is As the control power source; and when the primary power signal is disabled and the preliminary power enable signal is enabled, the standby power source is used as the control power source. The fan control method according to claim 7, wherein the switching the first fan speed signal or the second fan speed signal as the speed control signal according to the speed switching signal comprises the following steps: receiving the speed switching signal and a normal Operating to the standby signal, when the normal operation to the standby signal is enabled, providing a rotation speed adjustment signal according to the rotation speed switching signal; generating a pulse width modulation signal of the fixed clock as the second fan rotation speed signal; and receiving and relieving The speed adjustment signal switches the first fan speed signal or the second fan speed signal as the speed control signal. The fan control method as described in claim 7 of the patent scope further includes: Detecting the fan enable signal, when detecting that the fan enable signal is disabled in the standby state of the computer device, counting for a predetermined period; after the predetermined period has been counted, the fan enable signal is still not After being enabled, the forced operation signal is provided during the forced operation period; the control power is supplied to the fan according to the forced operation signal; and the second fan rotation speed signal is provided as the rotation speed control signal according to the forced operation signal to the a fan; and continuously detecting the fan enable signal after the forced operation period.