Samsung 275TPLUS - Manual (Page 42)

Changing the source is only allowed for external devices that are connected to the
monitor at the time.
PIP ( Available in PC/DVI(PC) Mode Only )
Menu Description
PIP
Push the PIP button to turn PIP screen On/Off.
You can view a picture from AV, S-Video, or Component through the PIP
screen in PC and DVI (PC) mode.
OSD Function
Input