A fastening apparatus for fastening a first device to a second device is disclosed. The apparatus comprises a standoff member disposed through a through hole of the first device; a clamp member having a clamp portion for clamping the standoff member; a sleeve member having a hollow body and enclosing the clamp member, wherein the clamp member is compressed in the hollow body; a resilient member wrapping around the sleeve member; a rotatable cam member pivotly coupled to the clamp member; and a cap member arranged between the rotatable cam member and the resilient member, wherein the rotatable cam member is rotated to a first location to compress the resilient member for causing a first preload force exerted on the second device.