A computer device and a multi-computer system are provided. The computer device includes a central processing unit (CPU), a wireless connection circuit, and a switch circuit. The CPU is coupled to a display to provide an enabling display signal to the display according to a hot plug detection signal provided from the display. The wireless connection circuit receives one of a wireless connection signal and a wireless disconnection signal from a wireless input device. The switch circuit is coupled between the display and the CPU and coupled to the wireless connection circuit. The switch circuit provides the hot plug detection signal to the CPU when the wireless connection circuit receives the wireless connection signal, and masks the hot plug detection signal from the CPU when the wireless connection circuit receives the wireless disconnection signal.