Computer power supply unit with output mode determining function

A computer power supply unit with output mode determining function, comprising:

• a voltage difference amplification circuit having a first input end, a second input end and an output end, a diode being disposed between the first and second input ends;
• a comparison circuit having a first input end, a second input end and an output end, the second input end of the comparison circuit being connected to the output end of the voltage difference amplification circuit;
• a linear voltage regulator circuit having a first end and a second end, the first end of the linear voltage regulator circuit being connected to the first input end of the voltage difference amplification circuit, the second end of the linear voltage regulator circuit being connected to the first input end of the comparison circuit to output a constant voltage;
• a drive circuit having a first input end, a second input end and an output end, the first input end of the drive circuit being connected to the output end of the comparison circuit;
• and
• a clamp circuit having an input end, a first output end and a second output end, the input end of the clamp circuit being connected to the output end of the drive circuit, according to whether the diode generates turn-on bias, the voltage difference amplification circuit outputting a first voltage level, according to the first voltage level and the value of the constant voltage, the comparison circuit outputting a second voltage level, whereby according to the value of the second voltage level, the drive circuit drives or does not drive the clamp circuit so as to judge the output mode of the power supply unit.