A pipeline pig support rack apparatus includes a frame having a plurality of supports mounted thereon, each extending upwardly from the frame. The blocks may include logic circuits that operate at different clock rates. When no current flows, the follower disk is separated from the drive disk to cut off the power transmission from the driving unit to the door-openingclosing mechanism. The first slot can be positioned near the edge of the motherboard, further facilitating heat dissipation and access to the slot.