Motherboards and cards (herein "boards") mounted in computer enclosures must be supported on X, Y and Z axes to resist shock and vibration. This requires that four edges of the board be supported. Because of the high cost of such boards their lengths are made as small as possible, and this dimension is the direction of insertion of the board. A guide is attached to the leading edge of the board having a depending foot which engages fasteners formed on the base of the chassis of the enclosure. Thus the inner edge of the board is supported along two axes. Two side edges of the board are held in tracks and the outer edge is held at the point of insertion.