An electronic device may include a circuit board, a heat generating component carried by the circuit board, a heat transfer rail extending along an edge of circuit board and coupled to the heat generating component, a housing covering the circuit board, and a heat transfer clamp between the heat transfer rail and the housing. The heat transfer clamp includes a flexible, heat conductive layer having a first portion in thermal contact with the heat transfer rail and a second portion in thermal contact with the housing. The first and second portions are thermally coupled, and a clamp and a compressible layer thereon extends between the first and second portions of the flexible, heat conductive layer.