A drive circuit of a computer system is for driving a mode indicator. The computer system includes a first port and a second port. The mode indicator includes a first receiving end and a second receiving end. The drive circuit includes a first input end connected to the first port, a second input end connected to the second port, a first output end connected to the first receiving end, a second output end connected to the second receiving end. A power supply is connected to the first input end and the second input end via a first resistor and a second resistor respectively. The mode indicator is dichromatic and has two LEDs emitting non-matching colored light.