Computer system

A computer system including a graphic chipset generating RGB signals characterizing RGB components, and an output port through which the RGB signals are transmitted from the graphic chipset to a display device, further including an EMI filter to filter EMI from the RGB signals generated by the graphic chipset, and to transmit the filtered RGB signals to the output port; a definition improver to adjust an output level of the RGB signals generated by the graphic chipset to a predetermined output level, and to transmit the adjusted RGB signal to the output port; and a selection switch to selectively connect an output terminal of the graphic chipset with the EMI filter or the definition improver.