The invention relates to a server, which comprises a complex programmable logic device, a shielding and resetting unit and a switching unit, wherein the complex programmable logic device receives a power good signal and generates a switching signal, wherein after burning of the complex programmable logic device is finished, the server can generate a resetting signal so that the power good signal is in a resetting state, and the switching signal is in a suspension joint state; the shielding and resetting unit is connected with the complex programmable logic device and shields the switching signal according to the power good signal to generate a control signal, wherein the control signal has a fixed level; and the switching unit is connected with the shielding and resetting unit, receives afirst power source and a second power source, and switches the first power source or the second power source according to the control signal for being used as an output power source, thus, after burning of the complex programmable logic device is finished, the switching unit can accurately switch the output power source.