That would seem rather self explanatory, but if it has an internal ps, then it has a regular 3 pin IEC power cord that plugs straight into the unit. If it has an external ps, then it has a 9 pin, or some other type of connector that plugs into an EXTERNAL power supply, which then has the regular 3 pin power cord that goes to the wall. It may also just have the big "block" that plugs into the wall.