The invention provides a control apparatus, a main board, and a computer herein, the control apparatus is applied in the computing device. The computing device includes a main board a standby power supply, and a switching means configured between the standby power supply and the at least one electronic element. The control apparatus includes a signal receiving module, a judging module for judging whether the computing device is in a turn-off mode according to the signal, and a controlling module. The standby power supply is connected with the main board through the control apparatus and the switching switch respectively, so that after the turn-off of the computer, the control apparatus switches off the connection between the standby power supply and the main board, to reduce the power consumption of the main board after the turn-off.