A voltage margin testing blade is adapted for use in a bladed server having at least one internal adjustable power supply. The testing blade is further adapted to provide a control signal to the power supply indicative of any desire to modify the output voltage of the power supply. The testing blade senses the output voltage of the power supply and compares it to a desired power supply voltage. The control signal is generated in response to this comparison in order to control the actual power supply voltage at or about the desired power supply voltage.