Most low-power supplies without internal fans are designed to be placed horizontally. If there is a problem with the system structure, it is necessary to place the power supply vertically, because the heat dissipation issue should consider the output power at a higher ambient temperature. Use with deduction (refer to product specifications). As for the model with a cooling fan inside the power supply, there is no difference in the installation method whether it is horizontal or vertical, or if the applied system has an independent forced cooling fan to provide proper heat dissipation for the power supply, the installation method is also the same. There is no difference.