Samsung SP-P400B - Manual (Page 20)

Connect [PC IN] port on the rear side of the projector to the monitor output port of the PC using a PC video cable.
When connections are all completed, connect both power codes of the projector and the PC.
Connect the [VIDEO/PC AUDIO IN] input port of the projector to the speaker output ports of the PC using an audio
cable.
This product supports plug and play and therefore, if you use Window XP you do not need to setup the driver
on your PC.
Using the Projector
Turn on the projector and press the [SOURCE] button to select <PC>.
PC Mode is not available, check PC video cable is in place.
Turn on the PC and set the PC Environment when necessary.
Adjust the screen.( Auto Adjustment )
Connecting Headphones
Connect the jack of the headphones to the input terminal [ ] on the back of the projector.