How do you install power unit in dell 8400?

To install the power unit in a DELL 8400, first, ensure the computer is turned off and unplugged. Open the computer case by removing the side panel screws and sliding the panel off. Locate the power supply unit (PSU), disconnect all cables connected to it, unscrew it from the chassis, and remove it. Then, place the new power supply in the same position, secure it with screws, and reconnect all necessary cables before closing the case.