A bus ring-back and voltage over-shoot reduction apparatus with capability for rendering an expansion slot of a computer system hot-pluggable, wherein a logic gate controls a switching element so that when the element is turned on, the input and output (I/O) nodes of the element are in a low ohmic conductive relationship. One of the I/O nodes is coupled to an expansion card whereas the other node is coupled to a bus to which the expansion slot is connected. The apparatus operates as a level shifter wherein the output node voltage follows the input node voltage until pinch-off such that the output voltage remains substantially stable thereafter. The apparatus also isolates the expansion card from the bus when the system is running or during the powering up of the card.