This paper describes the efficiency of the fast electromagnetic simulation method for analysing the PCBs. This method is constructed by combination of the multi graphics processing unit (GPU) systems and the weakly conditionally stable algorithms. The weakly conditionally method is faster than the conventional ones in the case of fine cell including the computational domain. In addition, this method is suitable for parallel implementation with multi-GPU computing. First, the weakly conditionally stable algorithm is described briefly. Second, this method is shown. Finally, the efficiency of the multi-GPU based method is verified by analysing an example of the practical PCB.